Channel Access
< kazuro.furukawa @ kek.jp >
Introduction to
Channel Access
Kazuro Furukawa
<kazuro.furukawa@kek.jp>
for EPICS Seminar at J-PARC
March 14, 2012
Based on presentations by
Kenneth Evans, Jr., 2004
Kazuro Furukawa, 2006
Kay Kasemir, 2007
Kazuro Furukawa, 2010
<http://www-linac.kek.jp/cont/epics/>
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
1
Channel Access
概要
Controls
Channel Access Concepts
Channel Access API
Simple CA Client
Simple CA Client with Callbacks
(EPICS Build System)
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
2
Channel Access
加速器の制御
なぜ制御が必要か、制御で何をするのか
粒子の軌道を変えるための電磁石の制御の例から
考えてみよう
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
3
Channel Access
電磁石を使って粒子の軌道を制御しよう (1)
まずお試し用の電磁石で練習しようか
電流変更するためのつまみと電流メータを使おう
去年測った電流と磁場の関係のグラフを探さなきゃ…
 見つけたけど、いちいち読み取るのは面倒だなあ…
メータの針では精度がないからデジタル表示にしよう
PC で軌道計算をしてから設定しなくちゃ
あれ、電源がオフになった
 なんだコイルの熱を冷やすのに水を流すのか…
水の表示器を置いておこう
間違って電流値を大き掛け過ぎたら、またオフになった
 電源を壊さないように過電流の制限に引っかかったんだ
さっきと同じ電流値にしても正しい磁場にならないぞ
 鉄芯のヒステリシスで電流と磁場の関係が変わっちゃった
電流を上げたり下げたりして初期化しよう
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
4
Channel Access
電磁石を使って粒子の軌道を制御しよう (2)
本物の粒子の軌道を曲げてみよう
 あれ、本物の電磁石は 1km も離れているのか
 しょうがない配線しよう
 あれ、電磁石って何百台もあるの、ひえっー
 とても全部配線できないよ
しょうがない、切り替え器を使って一個のつまみと一個のメータでたくさんの
電磁石を扱えるようにしよう
 あったまいいー
入射器からリングに粒子を入射してと
 あれ、うまく周回してくれないよ
ビームモニタの情報を PC に送って、軌道計算して、電磁石の磁場を調整し
なくちゃ
 ええっ、何百台もの電磁石の、制限値に注意して、磁場特性の変換をして、一度に、設定
しなくてはいけないの
 そんなことひとりでできないよ…
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
5
Channel Access
粒子を制御しよう
というわけで、
 制御インターフェース群：加速器装置の情報解釈など
 ネットワーク：情報伝送、タイミング伝送
 計算機群：軌道計算、情報管理 (表示、操作、記録) など
を使うことになった
制御システムを使用すれば
 ビームモニタからの情報を参照して、
 シミュレーション計算結果と比較して、
 マイクロ波装置や偏向、収束、補正電磁石などを操作して、
 粒子ビームを自在に操り、
粒子加速器の性能を最大限に発揮して
みんなに有効な実験結果を導くことが可能、かも．．．
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
6
Channel Access
KEKB Operation Improvement (base of SuperKEKB)
Belle/KEK
May.2000
Apr.2003
Dual Bunch e+
Feb.2005
Continuous
Injections
Dec.2008
Crab Cavities and
Simultaneous Injection
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
7
Channel Access
大型物理実験装置
数十人から数千人規模の研究者が関わる物理実験装置
素粒子物理学実験、光学・電波天文台、プラズマ核融合、など
ほとんどが国際協力で予算獲得、建設、運用
例えば、素粒子のジュネーブ CERN/LHC、核融合のカダラッシュ
ITER、天文のチリ ALMA などアジア、ヨーロッパ、アメリカの国際協力
で実現しているものは多い
関連した国際会議が開かれている、来年 10 月は米国 (サンフランシスコ)
LHC/CERN
EPICS Seminar at J-PARC
ITER/JAEA
Kazuro Furukawa, KEK, Mar.2012.
8
Channel Access
制御システムの目標 (の例)
信頼性が高くかつ柔軟な制御処理機構を道具として
提供する
性能を高めるための (実時間) 自動処理
モデリング・シミュレーション
新しい問題に対する迅速な対処
情報の交換・管理
データ解析
安全機構
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
9
Channel Access
EPICS
たくさんの制御システムが同じ問題を抱えていたのに、違う
ハードウェア/ソフトウェアを使い違った方法で解決しようとして
いた
そこで EPICS が開発された
ほとんどの制御についての要求が満たされる
Closed Loop / Open Loop
Logical Value Conversion
Synchronous / Asynchronous
Programless / Performance
Display / Archive / Analysis
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
10
Channel Access
KEKB and Controls
制御用ソフトウェア EPICS
 以前はほとんどが内製ソフトウェアの組み合わせ
RPC, CORBA, …
 徐々に共通ソフトウェアに移行してきた
KEK では 1994 年から “EPICS” と呼ばれる国際共同開発のソフトウェアへ
 BSD-like な Open-source、多数の研究所が採用
 SCADA や Labview などとほぼ同等またはそれ以上の機能
 他に CORBA を基本としたものなどもある
当初は中間層と全体制御の間で EPICS を利用していた
現在は小型コントローラにも内蔵するようになってきている
 最近 ITER (プラズマ核融合) も採用を決める
 上位ソフトウェアはスクリプト言語で書かれるものも多い
粒子加速器の物理の記述が行えて Mathematica 文法に近い “SADscript” とい
うソフトウェアが多用される
他に Python や Perl、Tcl なども
 下位ソフトウェアは C++ や C が多い
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
11
Channel Access
EPICS
EPICS を使用すると
これまで各研究所で作られていた制御のためのプログラムを個別に書
いたり、保守したりする必要がなくなる
よりよく考慮された設計になっている可能性が高い
当初は考えていなかった制御が必要になることは多い
多様な制御方式に対応できる
多様なアプリケーションプログラムを使用できる
他のグループからの支援を得られる可能性がある
国際的に貢献できる可能性がある
x 最新のソフトウェア技術の利用が制限される
オブジェクト指向プログラミング、CORBA、とか
部分的に使用することは可能
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
12
Channel Access
チャネルアクセスの参考書
以降の Slide は Channel Access (CA) の概略説明
より深く調べるときには
EPICS の web page を覗いてみる
http://www.aps.anl.gov/epics/index.php
Look under Documents
Also under Base, then a specific version of Base
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
15
Channel Access
EPICS システムの構成
MEDM
MEDM
Client
Client
Client
MEDM
Channel Access
Server
EPICS Seminar at J-PARC
IOC
IOC
IOC
Meter
Power Supply
Camera
Kazuro Furukawa, KEK, Mar.2012.
16
Channel Access
Search and Connect の手続き
MEDM
MEDM
Client
Client
Client
MEDM
3. TCP Connection
Let’s talk !
2. UDP Reply
1.
UDP Broadcast Sequence
Who has it ?
I have it !
Server
Check
EPICS Seminar at J-PARC
IOC
Check
IOC
Check
IOC
IOC
Check
Meter
Power Supply
Camera
Kazuro Furukawa, KEK, Mar.2012.
17
Channel Access
Channel Access の動作
“connection
request” or
“search request”
Channel Access Client
Who has a PV named
“S1A:H1:CurrentAO”?
“get”
or
“caget”
What is its
value?
“put” or
“caput”
“set a monitor”
Change its
value to 30.5
Notify me when the value
changes
CA Client
CA Server
Channel Access Server
I do.
25.5
AMPS
Process Variables:
OK, it is now
30.5
It is now
20.5
AMPS
It is
now
10.5
AMPS
It is now
0.0023
AMPS
“put complete”
S1A:H1:CurrentAO
S1:P1:x
or
S1:P1:y
S1:G1:vacuum
EPICS Seminar at J-PARC
or
30.5 is too high. It is
now set to the
maximum value of
27.5.
“post an event”
or
“post a monitor”
You are not
authorized to change
this value
Kazuro Furukawa, KEK, Mar.2012.
18
Channel Access
Search 要求
Client からの Search 要求は UDP の Packet から成る
Only goes to EPICS_CA_ADDR_LIST
Starts with a small interval (30 ms), that doubles each time
Until it gets larger than 5 s, then it stays at 5 s
Stops after 100 packets or when it gets a response
Never tries again until it sees a beacon anomaly or creates a new PV
Total time is about 8 minutes to do all 100
全ての Server は指定 PV が存在するかどうか調べる
普通は最初 (または少数の) の要求 Packet で接続が確立できる
存在しない PV を要求すると、多量の Traffic を生じる
Try to eliminate them
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
20
Channel Access
Beacon
Beacon は Server から送られる UDP broadcast packet
正常時には, 個々の Server は一定時間間隔で UDP Beacon を
broadcast する (like a heartbeat)
EPICS_CA_BEACON_PERIOD, 15 s by default
Server の起動時には, Server は連続した UDP beacon を
broadcast する
Starts with a small interval (25 ms, 75 ms for VxWorks)
Interval doubles each time
Until it gets larger than 15 s, then it stays at 15 s
Takes about 10 beacons and 40 s to get to steady state
Client はその beacon を監視し続ける
Determine connection status, whether to reissue searches
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
21
Channel Access
Virtual Circuit の切断






3.14 5 and later
Hang-up message from server
TCP connection is closed
MEDM screens go white
Clients reissue search requests
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
22
Channel Access
Virtual Circuit の無応答
3.14.5 and later
No response from server for 30 sec.
Client then sends “Are you there” query
If no response for 5 sec, TCP connection is not closed
For several hours, at least
MEDM screens go white
Clients do not reissue search requests
Helps with network storms
Clients that do not call ca_poll frequently get a virtual circuit
disconnect even though the server may be OK
Clients written for 3.13 but using 3.14 may have a problem
May be changed in future versions
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
23
Channel Access
重要な環境変数 (Environment Variable)
EPICS_CA_ADDR_LIST
Determines where to search
Is a list (separated by spaces)
“123.45.1.255 123.45.2.14 123.45.2.108”
Default is broadcast addresses of all interfaces on the host
Works when servers are on same subnet as Clients
Broadcast address
Goes to all servers on a subnet
Example: 123.45.1.255
Use ifconfig –a on UNIX to find it (or ask an administrator)
EPICS_CA_AUTO_ADDR_LIST
YES: Include default addresses above in searches
NO: Do not search on default addresses
If you set EPICS_CA_ADDR_LIST, usually set this to NO
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
24
Channel Access
EPICS_CA_ADDR_LIST
MEDM
MEDM
Client
Client
Client
Broadcast
Specific
123.45.1.255
123.45.2.108
Subnet 1
Server
EPICS Seminar at J-PARC
MEDM
Subnet 2
IOC
Not Included
IOC
IOC
Meter
Power Supply
Camera
Kazuro Furukawa, KEK, Mar.2012.
25
Channel Access
その他の環境変数
CA Client
CA Server
EPICS_CA_ADDR_LIST
EPICS_CA_AUTO_ADDR_LIST
EPICS_CA_CONN_TMO
EPICS_CA_BEACON_PERIOD
EPICS_CA_REPEATER_PORT
EPICS_CA_SERVER_PORT
EPICS_CA_MAX_ARRAY_BYTES
EPICS_TS_MIN_WEST
EPICS_CAS_SERVER_PORT
EPICS_CAS_AUTO_BEACON_ADDR_LIS
T
EPICS_CAS_BEACON_ADDR_LIST
EPICS_CAS_BEACON_PERIOD
EPICS_CAS_BEACON_PORT
EPICS_CAS_INTF_ADDR_LIST
EPICS_CAS_IGNORE_ADDR_LIST
さらに詳しくは Channel Access Reference
Manual を参照
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
26
Channel Access
Release 3.13 の 3.14 の似ている部分





EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
27
Channel Access
Release 3.13 と 3.14 の違い
3.14 is threaded
Your program does not have to be threaded
3.14 has different names for some functions
ca_context_create for ca_task_initialize
ca_context_destroy for ca_task_exit
ca_create_channel for ca_search_and_connect
ca_create_subscription for ca_add_event
ca_clear_subscription for ca_clear_event
The new functions may have more capabilities, usually related to
threading
We will use the new names
3.14 has a different mechanism for lost connections
Virtual circuit unresponsive (Not available in 3.13)
Virtual circuit disconnected
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
28
Channel Access
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
29
Channel Access
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
30
Channel Access
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
31
Channel Access
CA (Channel Access) の
API (Application Program Interface)
The main CA client interface is the "C" library that
comes with EPICS base
Internally uses C++, but API is pure C.
Almost all other CA client interfaces use that C
library
Exception: New pure Java JAC
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
32
Channel Access
基本的な Channel Access Client の手続き
Initialize Channel Access
ca_task_initialize or ca_context_create
Search
ca_search_and_connect or ca_create_channel
Do get or put
ca_get or ca_put
Monitor
ca_add_event or ca_create_subscription
Give Channel Access a chance to work
ca_poll, ca_pend_io, ca_pend_event
Clear a channel
ca_clear_channel
Close Channel Access
ca_task_exit or ca_context_destroy
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
33
Channel Access
cadef.h
All C or C++ programs must include cadef.h
#include <cadef.h>
You can look at this file to get more insight into
Channel Access
This presentation will use C examples
We will try to emphasize concepts, not the language
Even if you do not use C, it is important to understand
what is going on behind what you do use
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
34
Channel Access
ca_context_create
enum ca_preemptive_callback_select {
ca_disable_preemptive_callback,
ca_enable_preemptive_callback };
int ca_context_create (
enum ca_preemptive_callback_select SELECT );
Should be called once prior to any other calls
Sets up Channel Access
Use SELECT=ca_disable_preemptive_callback
Unless you intend to do threads
Can also use ca_task_initialize() for 3.13 compatibility
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
35
Channel Access
ca_context_destroy
void ca_context_destroy ();
Should be called before exiting your program
Shuts down Channel Access
Can also use ca_task_exit() for 3.13
compatibility
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
36
Channel Access
ca_create_channel
typedef void caCh (struct connection_handler_args ARGS);
int ca_create_channel (
const char *PVNAME,
caCh *CALLBACK,
void *PUSER,
capri PRIORITY,
chid *PCHID );
Sets up a channel and starts the search process
PVNAME is the name of the process variable
CALLBACK is the name of your connection callback (or NULL)
The callback will be called whenever the connection state changes,
including when first connected
Information about the channel is contained in ARGS
Use NULL if you don’t need a callback
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
37
Channel Access
ca_create_channel, cont’d
typedef void caCh (struct connection_handler_args ARGS);
int ca_create_channel (
const char *PVNAME,
caCh *CALLBACK,
void *PUSER,
capri PRIORITY,
chid *PCHID );
PUSER is a way to pass additional information
Whatever you have stored at this address
It is stored in the chid
In C++ it is often the this pointer for a class
Use NULL if you don’t need it
Use PRIORITY=CA_PRIORITY_DEFAULT
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
38
Channel Access
ca_create_channel, cont’d
typedef void caCh (struct connection_handler_args ARGS);
int ca_create_channel (
const char *PVNAME,
caCh *CALLBACK,
void *PUSER,
capri PRIORITY,
chid *PCHID );
A chid is a pointer to (address of) an opaque struct used by Channel
Access to store much of the channel information
chanId is the same as chid (typedef chid chanId;)
PCHID is the address of the chid pointer (Use &CHID)
You need to allocate space for the chid before making the call
Channel Access will allocate space for the struct and return the address
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
39
Channel Access
ca_create_channel, cont’d
typedef void caCh (struct connection_handler_args ARGS);
int ca_create_channel (
const char *PVNAME,
caCh *CALLBACK,
void *PUSER,
capri PRIORITY,
chid *PCHID );
Use macros to access the information in the chid
ca_name(CHID) gives the process variable name
ca_state(CHID) gives the connection state
ca_puser(CHID) gives the PUSER you specified
Etc.
The ARGS struct in the connection callback includes the chid
Can also use ca_search_and connect() for 3.13 compatibility
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
40
Channel Access
ca_clear_channel
int ca_clear_channel (chid CHID);
Shuts down a channel and reclaims
resources
Should be called before exiting the program
CHID is the same chid used in
ca_create_channel
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
41
Channel Access
ca_array_get
int ca_array_get (
chtype TYPE,
unsigned long COUNT,
chid CHID,
void *PVALUE );
Requests a scalar or array value from a process variable
Typically followed by ca_pend_io
TYPE is the external type of your variable
Use one of the DBR_xxx types in db_access.h
E.g. DBR_DOUBLE or DBR_STRING
COUNT is the number of array elements to read
CHID is the channel identifier from ca_create_channel
PVALUE is where you want the value(s) to go
There must be enough space to hold the values
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
42
Channel Access
ca_array_get_callback
typedef void ( *pCallBack ) (struct event_handler_args
ARGS);
int ca_array_get_callback (
chtype TYPE,
unsigned long COUNT,
chid CHID,
pCallBack USERFUNC,
void *USERARG );
Requests a scalar or array value from a process variable,
using a callback
TYPE is the external type of your variable
Use one of the DBR_xxx types in db_access.h
E.g. DBR_DOUBLE or DBR_STRING
COUNT is the number of array elements to read
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
43
Channel Access
ca_array_get_callback, cont’d
typedef void ( *pCallBack ) (struct event_handler_args
ARGS);
int ca_array_get_callback (
chtype TYPE,
unsigned long COUNT,
chid CHID,
pCallBack USERFUNC,
void *USERARG );
CHID is the channel identifier from ca_create_channel
USERFUNC is the name of your callback to be run when the
operation completes
USERARG is a way to pass additional information to the
callback
struct event_handler_args has a void *usr member
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
44
Channel Access
ca_array_put
int ca_array_put (
chtype TYPE,
unsigned long COUNT,
chid CHID,
const void *PVALUE);
Requests writing a scalar or array value to a process variable
Typically followed by ca_pend_io
TYPE is the external type of your supplied variable
Use one of the DBR_xxx types in db_access.h
E.g. DBR_DOUBLE or DBR_STRING
COUNT is the number of array elements to write
CHID is the channel identifier from ca_create_channel
PVALUE is where the value(s) to be written are found
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
45
Channel Access
ca_array_put_callback
typedef void ( *pCallBack ) (struct event_handler_args
ARGS);
int ca_array_put_callback (
chtype TYPE,
unsigned long COUNT,
chid CHID,
const void *PVALUE,
pCallBack USERFUNC,
void *USERARG );
Requests writing a scalar or array value to a process
variable, using a callback
TYPE is the external type of your variable
Use one of the DBR_xxx types in db_access.h
E.g. DBR_DOUBLE or DBR_STRING
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
46
Channel Access
ca_array_put_callback, cont’d
typedef void ( *pCallBack ) (struct event_handler_args ARGS);
int ca_array_put_callback (
chtype TYPE,
unsigned long COUNT,
chid CHID,
const void *PVALUE,
pCallBack USERFUNC,
void *USERARG );
COUNT is the number of array elements to write
CHID is the channel identifier from ca_create_channel
PVALUE is where the value(s) to be written are found
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
47
Channel Access
ca_array_put_callback, cont’d
typedef void ( *pCallBack ) (struct event_handler_args
ARGS);
int ca_array_put_callback (
chtype TYPE,
unsigned long COUNT,
chid CHID,
const void *PVALUE,
pCallBack USERFUNC,
void *USERARG );
USERFUNC is the name of your callback to be run when the
operation completes
USERARG is a way to pass additional information to the callback
struct event_handler_args has a void *usr member
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
48
Channel Access
ca_create_subscription
typedef void ( *pCallBack ) (struct event_handler_args
ARGS);
int ca_create_subscription (
chtype TYPE,
unsigned long COUNT,
chid CHID,
unsigned long MASK,
pCallBack USERFUNC,
void *USERARG,
evid *PEVID );
Specify a callback function to be invoked whenever the
process variable undergoes significant state changes
Value, Alarm status, Alarm severity
This is the way to monitor a process variable
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
49
Channel Access
ca_create_subscription, cont’d
typedef void ( *pCallBack ) (struct event_handler_args
ARGS);
int ca_create_subscription (
chtype TYPE,
unsigned long COUNT,
chid CHID,
unsigned long MASK,
pCallBack USERFUNC,
void *USERARG,
evid *PEVID );
TYPE is the external type you want returned
Use one of the DBR_xxx types in db_access.h
E.g. DBR_DOUBLE or DBR_STRING
COUNT is the number of array elements to monitor
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
50
Channel Access
ca_create_subscription, cont’d
typedef void ( *pCallBack ) (struct event_handler_args ARGS);
int ca_create_subscription (
chtype TYPE,
unsigned long COUNT,
chid CHID,
unsigned long MASK,
pCallBack USERFUNC,
void *USERARG,
evid *PEVID );
CHID is the channel identifier from ca_create_channel
MASK has bits set for each of the event trigger types requested
DBE_VALUE
DBE_LOG
DBE_ALARM
EPICS Seminar at J-PARC
Value changes
Exceeds archival deadband
Alarm state changes
Kazuro Furukawa, KEK, Mar.2012.
51
Channel Access
ca_create_subscription, cont’d
typedef void ( *pCallBack ) (struct event_handler_args
ARGS);
int ca_create_subscription (
chtype TYPE,
unsigned long COUNT,
chid CHID,
unsigned long MASK,
pCallBack USERFUNC,
void *USERARG,
evid *PEVID );
USERFUNC is the name of your callback to be run when the state
change occurs
USERARG is a way to pass additional information to the callback
struct event_handler_args has a void *usr member
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
52
Channel Access
ca_create_subscription, cont’d
typedef void ( *pCallBack ) (struct event_handler_args
ARGS);
int ca_create_subscription (
chtype TYPE,
unsigned long COUNT,
chid CHID,
unsigned long MASK,
pCallBack USERFUNC,
void *USERARG,
evid *PEVID );
PEVID is the address of an evid (event id)
You need to allocate space for the evid before making the call
Similar to a chid
Only used to clear the subscription (Can be NULL if not needed)
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
53
Channel Access
ca_clear_subscription
int ca_clear_subscription ( evid EVID );
Used to remove a monitor callback
EVID is the evid from ca_create_subscription
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
54
Channel Access
ca_add_exception_event
typedef void (*pCallback) (struct exception_handler_args ARGS );
int ca_add_exception_event (
pCallback USERFUNC,
void *USERARG );
Used to replace the default exception handler
USERFUNC is the name of your callback to be run when
an exception occurs
Use NULL to remove the callback
USERARG is a way to pass additional information to the
callback
struct exception_handler_args has a void *usr member
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
55
Channel Access
Request Handling
The preceding routines are requests
They only queue the operation
They hardly ever fail
The return values are almost always ECA_NORMAL
(But they should be checked)
These requests are only processed when one of the
following is called
ca_pend_io
ca_pend_event
ca_poll
Blocks until requests are processed
Blocks a specified time
Processes current work only
If these routines are not called, the requests are not
processed and background tasks are also not processed
The rule is that one of these should be called every 100 ms
To allow processing of background tasks (beacons, etc.)
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
56
Channel Access
ca_pend_io
int ca_pend_io (double TIMEOUT);
Flushes the send buffer
Blocks for up to TIMEOUT seconds until
Outstanding gets complete
Searches with no callback have connected
Returns ECA_NORMAL when gets and searches are complete
Returns ECA_TIMEOUT otherwise
Means something went wrong
Get requests can be reissued
Search requests can be reissued after ca_clear_channel
Channel Access background tasks are performed
Unless there were no outstanding I/O requests
Use with searches, gets, and puts that don’t use callbacks
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
57
Channel Access
ca_pend_event
int ca_pend_event (double TIMEOUT);
Flushes the send buffer
Process background tasks for TIMEOUT seconds
Does not return until TIMEOUT seconds have elapsed
Use this when your application doesn’t have to
do anything else
Use ca_pend_event instead of sleep
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
58
Channel Access
ca_poll
int ca_poll ();
Flushes the send buffer
Process outstanding tasks only
Exits when there are no more outstanding tasks
Otherwise similar to ca_pend_event
Use this when your application has other things
to do
E.g. most GUI programs
Be sure it is called at least every 100 ms
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
59
Channel Access
CHID Macros
chtype ca_field_type ( CHID );
unsigned ca_element_count ( CHID );
char *ca_name ( CHID );
void *ca_puser ( CHID );
void ca_set_puser ( chid CHID, void *PUSER );
enum channel_state ca_state ( CHID );
enum channel_state {
cs_never_conn,
Valid chid, server not found or
unavailable
cs_prev_conn, Valid chid, previously connected to server
cs_conn,
Valid chid, connected to server
cs_closed }; Channel deleted by user
char *ca_host_name ( CHID );
int ca_read_access ( CHID );
int ca_write_access ( CHID );
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
60
Channel Access
ca_connection_handler_args
struct ca_connection_handler_args {
chanId chid;
Channel id
long op;
CA_OP_CONN_UP or
CA_OP_CONN_DOWN
};
Used in connection callback
Note chanId is used rather than chid
Some compilers don’t like chid chid;
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
61
Channel Access
event_handler_args
typedef struct event_handler_args {
void *usr;
User argument supplied with request
chanId chid;
Channel ID
long type;
The type of the item returned
long count;
The element count of the item returned
const void *dbr;
A pointer to the item returned
int status;
ECA_xxx status of the requested op
} evargs;
Used in get, put, and monitor callbacks
Do not use the value in dbr if status is not ECA_NORMAL
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
62
Channel Access
Channel Access API 関数の一覧
ca_add_exception_event
ca_attach_context
ca_clear_channel
ca_clear_subscription
ca_client_status
ca_context_create
ca_context_destroy
ca_context_status
ca_create_channel
ca_create_subscription
ca_current_context
ca_dump_dbr()
ca_element_count
ca_field_type
ca_flush_io
ca_get
ca_host_name
ca_message
ca_name
ca_read_access
ca_replace_access_rights_event
ca_replace_printf_handler
ca_pend_event
ca_pend_io
ca_poll
ca_puser
ca_put
ca_set_puser
ca_signal
ca_sg_block
ca_sg_create
ca_sg_delete
ca_sg_get
ca_sg_put
ca_sg_reset
ca_sg_test
ca_state
ca_test_event
ca_test_io
ca_write_access
channel_state
dbr_size[]
dbr_size_n
dbr_value_size[]
dbr_type_to_text
SEVCHK
ca_search
ca_search_and_connect
ca_task_exit
ca_task_initialize
Deprecated
ca_add_event
ca_clear_event
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
63
Channel Access
Ubuntu で試してみよう
 Warning
Bellow should be tried without real network
Normally, you should follow the institute rules
Running “excas” all the time is bad
 Boot Ubuntu Linux from USB memory
 Applications -> Accessories -> Terminal
sudo ifconfig eth0 192.168.1.2
ping 192.168.1.2
excas –p z: &
caget z:fred z:freddy z:jane z:janet
 After you finish
killall excas
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
64
Channel Access
makeBaseApp.pl を使えば簡単
Includes a template for basic CA client in C:
Start with this:
echo $PATH $EPICS_HOST_ARCH $EPICS_CA_ADDR_LIST
cd ; mkdir cac ; cd cac
makeBaseApp.pl -t caClient cacApp
make 2>&1 | tee make.log
Result:
bin/linux-x86/caExample <some PV>
bin/linux-x86/caMonitor <file with PV list>
 cd bin/linux-x86
 ./caExample z:fred
 echo z:fred > alist
 echo z:freddy >> alist
 ./caMonitor alist
Then read the sources, compare with the reference manual, and
edit/extend to suit your needs.
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
65
Channel Access
makeBaseApp の caExample.c
Minimal CA client program.
Fixed timeout, waits until data arrives.
Requests everything as 'DBR_DOUBLE'.
… which results in values of C-type 'double'.
See db_access.h header file for all the DBR_…
constants and the resulting C types or structures.
In addition to the basic DBR_<type> requests, it is
possible to request packaged attributes like
DBR_CTRL_<type> to get { value, units, limits, …} in one
request.
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
66
Channel Access
makeBaseApp の caMonitor.c
Better CA client program.
Registers callbacks to get notified when
connected ot disconnected
Subscribes to value updates instead of waiting.
… but still uses the same data type (DBR_STRING)
for everything.
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
67
Channel Access
理想的な CA client?
Use callbacks for everything
no idle 'wait', no fixed time outs.
Upon connection, check the channel's native type (int,
double, string, …)
to limit the type conversion burden on the IOC.
… request the matching DBR_CTRL_<type> once
to get the full channel detail (units, limits, …).
… and then subscribe to DBR_TIME_<type> to get updates of
only time/status/value
so now we always stay informed, yet limit the network traffic.
 Only subscribe once, not with each connection, because CA client
library will automatically re-activate subscriptions!
This is what EDM, archiver, … do.
Quirk: They don't learn about online changes of channel limits, units,
….
Doing that via a subscription means more network traffic, and CA
doesn't send designated events for 'meta information changed'.
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
68
Channel Access
Simple CA Client
Defines and includes
/* Simple CA client */
#define
#define
#define
#define
#include
#include
#include
#include
TIMEOUT 1.0
SCA_OK 1
SCA_ERR 0
MAX_STRING 40
<stdio.h>
<stdlib.h>
<string.h>
<cadef.h>
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
69
Channel Access
Simple CA Client
Function prototypes and global variables
/* Function prototypes */
int main(int argc, char **argv);
static int parseCommand(int argc, char **argv);
static void usage(void);
/* Global variables */
int pvSpecified=0;
char name[MAX_STRING];
char value[MAX_STRING];
double timeout=TIMEOUT;
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
70
Channel Access
Simple CA Client
Parse the command line
int main(int argc, char **argv)
{
int stat;
chid pCh;
/* Parse the command line */
if(parseCommand(argc,argv) != SCA_OK)
exit(1);
if(!pvSpecified) {
printf("No PV specified\n");
exit(1);
}
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
71
Channel Access
Simple CA Client
Initialize Channel Access
/* Initialize */
stat=ca_context_create(ca_disable_preemptive_callback);
if(stat != ECA_NORMAL) {
printf("ca_context_createfailed:\n%s\n",
ca_message(stat));
exit(1);
}
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
72
Channel Access
Simple CA Client
Request the search
/* Search */
stat=ca_create_channel(name,NULL,NULL,
CA_PRIORITY_DEFAULT,&pCh);
if(stat != ECA_NORMAL) {
printf("ca_create_channel failed:\n%s\n",
ca_message(stat));
exit(1);
}
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
73
Channel Access
Simple CA Client
Call ca-pend_io to process the search
/* Process search */
stat=ca_pend_io(timeout);
if(stat != ECA_NORMAL) {
printf(“search timed out after %g sec\n",
timeout);
exit(1);
}
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
74
Channel Access
Simple CA Client
Request the get
/* Get the value */
stat=ca_array_get(DBR_STRING,1,pCh,&value);
if(stat != ECA_NORMAL) {
printf("ca_array_get:\n%s\n",
ca_message(stat));
exit(1);
}
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
75
Channel Access
Simple CA Client
Call ca_pend_io to process the get
/* Process get */
stat=ca_pend_io(timeout);
if(stat != ECA_NORMAL) {
printf(“get timed out after %g sec\n",
timeout);
exit(1);
}
printf("The value of %s is %s\n",name,value)
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
76
Channel Access
Simple CA Client
Clean up
/* Clear the channel */
stat=ca_clear_channel(pCh);
if(stat != ECA_NORMAL) {
printf("ca_clear_channel failed:\n%s\n",
ca_message(stat));
}
/* Exit */
ca_context_destroy();
return(0);
}
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
77
Channel Access
SEVCHK
For simple error handling in test programs
SEVCHK ( <function call>, “message” )
Macro that checks return codes
If error, displays message and aborts
Used in example programs
DON’T use for robust clients
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
78
Channel Access
Simple CA Client
Output
simplecaget evans:calc
The value of evans:calc is 6
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
79
Channel Access
Simple CA Client with Callbacks
Defines and includes
/* Simple CA client with Callbacks */
#define
#define
#define
#define
TIMEOUT 1.0
SCA_OK 1
SCA_ERR 0
MAX_STRING 40
#include
#include
#include
#include
#include
<stdio.h>
<stdlib.h>
<time.h>
<string.h>
<cadef.h>
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
80
Channel Access
Simple CA Client with Callbacks
Function prototypes
/* Function prototypes */
int main(int argc, char **argv);
static void connectionChangedCB(struct connection_handler_args args);
static void valueChangedCB(struct event_handler_args args);
static char *timeStamp(void);
static int parseCommand(int argc, char **argv);
static void usage(void);
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
81
Channel Access
Simple CA Client with Callbacks
Global variables
/* Global variables */
int pvSpecified=0;
char name[MAX_STRING];
time_t curTime, startTime;
double timeout=TIMEOUT;
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
82
Channel Access
Simple CA Client with Callbacks
Parse the command line
int main(int argc, char **argv)
{
int stat;
chid pCh;
/* Parse the command line */
if(parseCommand(argc,argv) != SCA_OK)
exit(1);
if(!pvSpecified) {
printf("No PV specified\n");
exit(1);
}
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
83
Channel Access
Simple CA Client with Callbacks
Initialize Channel Access
/* Initialize */
stat=ca_context_create(ca_disable_preemptive_callback);
if(stat != ECA_NORMAL) {
printf("ca_context_createfailed:\n%s\n",
ca_message(stat));
exit(1);
}
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
84
Channel Access
Simple CA Client with Callbacks
Search
/* Search */
stat=ca_create_channel(name,connectionChangedCB,NULL,
CA_PRIORITY_DEFAULT,&pCh);
if(stat != ECA_NORMAL) {
printf("ca_create_channel failed:\n%s\n",
ca_message(stat));
exit(1);
}
printf("%s Search started for %s\n",timeStamp(),name);
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
85
Channel Access
Simple CA Client with Callbacks
Wait in ca_pend_event for the callbacks to occur
/* Wait */
startTime=curTime;
ca_pend_event(timeout);
printf("%s ca_pend_event timed out after %g sec\n",
timeStamp(),timeout);
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
86
Channel Access
Simple CA Client with Callbacks
Clean up
/* Clear the channel */
stat=ca_clear_channel(pCh);
if(stat != ECA_NORMAL) {
printf("ca_clear_channel failed:\n%s\n",
ca_message(stat));
}
/* Exit */
ca_context_destroy();
return(0);
}
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
87
Channel Access
Simple CA Client with Callbacks
Connection callback implementation
static void connectionChangedCB(struct
connection_handler_args args)
{
chid pCh=args.chid;
int stat;
/* Branch depending on the state */
switch(ca_state(pCh)) {
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
88
Channel Access
Simple CA Client with Callbacks
Connection callback implementation
case cs_conn:
printf("%s Connection successful\n",timeStamp());
stat=ca_array_get_callback(DBR_STRING,1,pCh,
valueChangedCB,NULL);
if(stat != ECA_NORMAL) {
printf("ca_array_get_callback:\n%s\n",
ca_message(stat));
exit(1);
}
break;
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
89
Channel Access
Simple CA Client with Callbacks
Connection callback implementation
case cs_never_conn:
printf("%s Cannot connect\n",timeStamp());
break;
case cs_prev_conn:
printf("%s Lost connection\n",timeStamp());
break;
case cs_closed:
printf("%s Connection closed\n",timeStamp());
break;
}
}
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
90
Channel Access
Simple CA Client with Callbacks
Value changed callback implementation
static void valueChangedCB(struct
event_handler_args args)
{
/* Print the value */
if(args.status == ECA_NORMAL && args.dbr) {
printf("%s Value is: %s\n",timeStamp(),
(char *)args.dbr);
printf("Elapsed time: %ld sec\n",
curTime-startTime);
}
}
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
91
Channel Access
Simple CA Client with Callbacks
Output
simplecagetcb evans:calc
Sep 14 18:31:55 Search started for evans:calc
Sep 14 18:31:55 Connection successful
Sep 14 18:31:55 Value is: 5
Elapsed time: 0 sec
Sep 14 18:31:56 ca_pend_event timed out after 1
sec
Time for this operation is typically a few ms
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
92
Channel Access
Simple Get Clients のソースファイルの例
Some of the code that is not related to Channel
Access has not been shown
All the files necessary to build a project as an
EPICS Extension should be available with the
presentation
Makefile
Makefile.Host
simplecaget.c
simplecagetcb.c
LICENSE
Stored as simpleCA.tar.gz
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
93
Channel Access
EPICS の Build システム
Supports both native and GNU compilers
Builds multiple types of components
libraries, executables, headers, scripts, java classes, …
Supports multiple host and target operating systems
Builds for all hosts and targets in a single <top> tree
epics/base
epics/extensions
Allows sharing of components across <top> trees
Has different rules and syntax for 3.13 and 3.14
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
94
Channel Access
System Requirements
必要な software
Perl version 5 or greater
GNU make, version 3.78.1/3.81 or greater
C++ compiler and linker (GNU or host vendor's
compiler)
場合によって必要な software
Tornado II and board support packages
RTEMS development tools and libraries
Motif, X11, JAVA, Tcl/Tk, Python…
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
95
Channel Access
User Requirements
Set an environment variable to specify the
architecture
EPICS_HOST_ARCH for 3.14
solaris-sparc, linux-x86_64, win32-x86, darwin-x86, etc.


Set the PATH so the required components can be
found
Perl, GNU make, C and C++ compilers
System commands (e.q. cp, rm, mkdir)
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
96
Channel Access
Internet 上の参考文書
Example files
http://www.aps.anl.gov/epics/
Documents - Training - Developing Client Tools
- Introduction to Chnnael Access Clients
- Example Files
Build examples of EPICS-Base, etc
on several Platforms
http://www-linac.kek.jp/cont/epics/win32/
http://www-linac.kek.jp/cont/epics/linux/
http://www-linac.kek.jp/cont/epics/darwin/
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
97
Channel Access
Channel-Access の簡単な例
Of course, this Presentation
makeBaseApp.pl -t caClient {app-name}
caExample.c
caMonitor.c
makeBaseEx.pl -t example {ext-name}
caExample.c
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
98
Channel Access
Typical Extensions Build Tree
epics/base
epics/extensions
config
configure
bin
solaris
solaris-sparc
lib
solaris
solaris-sparc
src
simpleCA
O.solaris
O.solaris-sparc
EPICS Seminar at J-PARC
<top> for base
<top> for extensions
3.13 configuration
3.14 configuration
Binaries by architecture
Libraries by architecture
Sources by application
Application source files
Binaries for this application
Kazuro Furukawa, KEK, Mar.2012.
99
Channel Access
Getting Started with an Extension
Make a directory structure for base
http://www.aps.anl.gov/epics/extensions/index.php
E.g. epics/base
Obtain base and build it
Set COMPAT_TOOLS_313 first if necessary (see later)
Make a directory structure for extensions
E.g. epics/extensions
Get extensions/config and configure from the EPICS pages
Set EPICS_BASE to your desired version of base

In extensions/configure/RELEASE for 3.14
Type gnumake (or make) in extensions
Get an extension and put it under extensions/src
Type gnumake (or make) in your application directory
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
100
Channel Access
Using the 3.13 Build Rules for Extensions














EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
101
Channel Access
Using the 3.14 Build Rules for Extensions
Go to the the EPICS page for your version of base
http://www.aps.anl.gov/epics/base/index.php
Read the README
It is very extensive
Should tell you everything you need to know
There is a only a Makefile and it uses 3.14 syntax
Set EPICS_HOST_ARCH for your platform
solaris-sparc, linux-x86, win32-x86, darwin-ppc, etc.
Configuration is in extensions/configure
RELEASE (Specifies what base)
os/CONFIG_SITE_xxx (Specifies local changes for xxx arch)
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
102
Channel Access
Makefile for Simple Get Clients
TOP = ../..
include $(TOP)/config/CONFIG_EXTENSIONS
include $(TOP)/config/RULES_ARCHS
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
103
Channel Access
Makefile.Host for Simple Get Clients
TOP = ../../..
include $(TOP)/config/CONFIG_EXTENSIONS
HOST_OPT = NO
CMPLR = STRICT
PROD = simplecaget simplecagetcb
PROD_LIBS = ca Com
ca_DIR = $(EPICS_BASE_LIB)
Com_DIR = $(EPICS_BASE_LIB)
simplecaget_SRCS += simplecaget.c
simplecagetcb_SRCS += simplecagetcb.c
include $(TOP)/config/RULES.Host
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
104
Channel Access
試してみる
自分の PC でもできるぞ
Virtual Linac
http://www.aps.anl.gov/epics/download/examples/index.php
http://www.aps.anl.gov/epics/download/examples/vlinac_multi.tgz
CSS
http://www-linac.kek.jp/cont/css/
http://www-linac.kek.jp/cont/css/apps/css_kek_3.1.0-linux.gtk.x86_64_20120226_010803.zip
http://www-linac.kek.jp/cont/css/apps/css_kek_3.1.0-linux.gtk.x86_20120226_010803.zip
もっと詳しくは
http://www.aps.anl.gov/epics/
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
105
Channel Access
試してみる
自分の PC でもできるぞ
Macintosh, Windows, Linux
例えば
http://www-linac.kek.jp/cont/epics/darwin/
http://www-linac.kek.jp/jisshu/
http://www-linac.kek.jp/cont/epics/
もっと詳しくは
http://www.aps.anl.gov/epics/
Application Developer’s Guide
Record Reference Manual
Channel Access Reference Manual
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
106
Channel Access
Acknowledgements
Jeff Hill [LANL] is responsible for EPICS Channel
Access and has developed almost all of it himself
Janet Anderson [ANL] is responsible for and has
developed most of the EPICS Build System
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
107
Channel Access
Thank You
EPICS Seminar at J-PARC
Kazuro Furukawa, KEK, Mar.2012.
108