PROFINET Real-Time
Communication
Functional Scope
Requirements
PROFINET
RT-Communication
IRT-Communication
TimeSynchronisation
IRT-Schedule
Unsynch-Comm.
Synchr.-Comm.
Software-Stack
RT and CBA
1
Real-Time Communication
© PROFIBUS
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1
PROFINET Real-Time Communication
PROFINET as Modular Technology
PROFINET Real-Time
Communication
MES
Motion
Control
Functional Scope
Requirements
Safety
Process
Automation
RT-Communication
IRT-Communication
TimeSynchronisation
IRT-Schedule
Unsynch-Comm.
Synchr.-Comm.
Verteilte
Automation
Decentral
Periphery
Fieldbus
Integration
Security
Software-Stack
RT and CBA
2
Network
Installation
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Network
Management
Real-time
Communication
WEB
Integration
2
PROFINET Real-Time Communication
PROFINET and Real-Time
PROFINET Real-Time
Communication
PROFINET CBA
PROFINET IO
Functional Scope
Requirements
RT-Communication
WEB-Services
IRT-Communication
TimeSynchronisation
IRT-Schedule
Unsynch-Comm.
Synchr.-Comm.
Software-Stack
RT and CBA
KomponentenBasierte
Kommunikation
Fill
Fill
3
IRT
Real-Time
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3
PROFINET Real-Time Communication
Requirements on Real-Time Communication
PROFINET Real-Time
Communication
•
● Refresh time: time duration from the switch over of a input
signal to the reaction on the correspondent output signal
Functional Scope
Requirements
● Factory Automation: 5-10 ms
● Motion Control: cycle time 1 ms, Jitter <1µs
RT-Communication
IRT-Communication
TimeSynchronisation
•
IRT-Schedule
Unsynch-Comm.
Synchr.-Comm.
The processor is responsible for the application and
should not be burdened by the real-time
communication excessively
● Main task is to handling the application program
Software-Stack
RT and CBA
Refresh times
•
The Real-Time communication must be 4able to be used
in existing Ethernet infrastructures
● No influence of the existing communication
● Use of standard network components (e.g. Switches)
● Use of standard Ethernet controllers in devices
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PROFINET Real-Time Communication
Real-Time Communication Classes
PROFINET Real-Time
Communication
Functional Scope
•
PROFINET distinguishes between two real-time classes
with differences regarding the performance:
•
Real-Time:
Requirements
RT-Communication
IRT-Communication
TimeSynchronisation
● Using standard components
IRT-Schedule
● Performance characteristics like fieldlbuses today (e.g. PROFIBUS)
Unsynch-Comm.
● Typical application area: Factory Automation
Synchr.-Comm.
Software-Stack
RT and CBA
•
Isochronous Real-Time:
● Clock synchronized communication
5
● Hardware support via Switch-ASIC
● Typical application area: drive control in Motion Control applications
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PROFINET Real-Time Communication
Improving Performance in the Communication Stack
PROFINET Real-Time
Communication
Functional Scope
Requirements
RT-Communication
IRT-Communication
TimeSynchronisation
IRT-Schedule
• The time needed for the provision and processing of the
data is independent of communication
• Improved performance is possible only through
optimization of the turnaround times in the stack
• The transmission speed on the line can be regarded as
negligible (100 Mb/s)
Producer
Unsynch-Comm.
Synchr.-Comm.
Software-Stack
∆T1
Provide
data
∆T2
Process
communication stack
Consumer
Process
data
RT and CBA
6
Process
communication stack
∆T3
Transmission
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PROFINET Real-Time Communication
Real-Time Communication
PROFINET Real-Time
Communication
RT
Factory Automation
Motion Control
Functional Scope
Requirements
RT-Communication
IRT-Communication
TimeSynchronisation
IRT-Schedule
Unsynch-Comm.
Synchr.-Comm.
Software-Stack
RT and CBA
100ms
10ms
<1ms
IT-Services
TCP/IP
Process data
Real-Time
• RT in PROFINET provides similar Real-Time properties
7
like PROFIBUS
• Cycle times can be realized in the range of 5 to 10 ms
• PROFINET Real-Time is fully compatible to TCP/IP
standard without any restriction
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PROFINET Real-Time Communication
Real-Time Communication
PROFINET Real-Time
Communication
1 Standard channel
Functional Scope
RT-Communication
IRT-Communication
TimeSynchronisation
IRT-Schedule
IT applications
e.g.
z HTTP
z SNMP
z DHCP...
PROFINET applications
1
Standard data
TCP/UDP
Unsynch-Comm.
Synchr.-Comm.
IP
2
Software-Stack
z
Device parameterization
and configuration
z
Reading of diagnostics
data
z
Negotiation of the
communication channel
for process data
Real-Time data
Real-time
Requirements
RT
2 Real-Time channel
RT
RT and CBA
Ethernet
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z
High-performance
8
transmission of
process data
z
Event-controlled signals
8
PROFINET Real-Time Communication
Construction of a PROFINET Real-Time-Frame
PROFINET Real-Time
Communication
Functional Scope
Requirements
RT-Communication
IRT-Communication
TimeSynchronisation
IRT-Schedule
Unsynch-Comm.
Synchr.-Comm.
Software-Stack
• Uniform Real-Time protocol for all applications
● Standardized frame format as defined in IEEE 802.3
● Specific Ethertype for PROFINET Real-Time frames
▪
0x0800: IP frame
0x8892: PROFINET Real-Time frame
● Assignment of received data over frame-ID
▪
cyclic transmission
a-cyclic transmission (Alarms and Events)
● Status of device and data (e.g. run, stop, error)
RT and CBA
9
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PROFINET Real-Time Communication
Construction of a PROFINET Real-Time-Frame
PROFINET Real-Time
Communication
Functional Scope
56 Bits
Requirements
Preamble SYNCH Dest
Addr
RT-Communication
8 Bits
6 Byte 6 Byte 2 byte 2 byte
Src
Addr
Tag
2 byte
2 byte
40..1440 bytes
Tag
Type
Frame
Control 8892H ID
User data
2 byte
1 byte
1 byte
4 byte
Cycle
Data Transfer FCS
Counter Status Status
Ethernet Frame (max. 1530 Bytes)
IRT-Communication
APDU-Status
TimeSynchronisation
VLAN Tag
IRT-Schedule
Unsynch-Comm.
Synchr.-Comm.
Software-Stack
RT and CBA
VLAN Tag
see next page
Type
Frame-ID
the identification for RT-Frame is (0x8892)
see next page
10
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Cycle Counter
will be incremented from the provider in 31,25µs-dteps.
Data Status
backup, primary, valid,invalid …
Transfer Status
reserved
10
PROFINET Real-Time Communication
Prioritization of Frames with the VLAN-Tag
PROFINET Real-Time
Communication
Min. is 64 bytes
Frame
Functional Scope
Requirements
Preamble
mit SFD
Dest Addr
Src Addr
Type
8892
Frame ID
Application data
CRC
RT-Communication
8 byte
6 byte
6 byte
2 byte
2 byte
<= 36*) …1472
4 byte
IRT-Communication
TimeSynchronisation
IRT-Schedule
Unsynch-Comm.
Synchr.-Comm.
Tag (optional)
Type
8100
Priority
0
VLAN-ID
Software-Stack
RT and CBA
2 byte
3-bit
1-bit
12-bit
VLAN-Tag
Acc. to 802.1 Q
(Usage is appl. specific)
11
*) maybe 40 byte because some switches remove the VLAN Tag
RT-Frames are always marked with a VLAN-Tag
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11
PROFINET Real-Time Communication
Distribution of Refresh Times
PROFINET Real-Time
Communication
n
RT
TCP/IP
Functional Scope
Requirements
RT-Communication
IRT-Communication
TimeSynchronisation
IRT-Schedule
Unsynch-Comm.
Synchr.-Comm.
Software-Stack
15%
100%
RT and CBA
12
10 msec
100 msec
t
• RT improvements against standard TCP/IP
•
•
•
© PROFIBUS
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Optimization of the absolute transmission time: factor 6-10
Minimization of the variance of the transmission times: factor 5-8
Improved behavior at replacement value: factor 7
12
PROFINET Real-Time Communication
Demands on Motion Control applications
PROFINET Real-Time
Communication
Functional Scope
Requirements
RT-Communication
IRT-Communication
TimeSynchronisation
IRT-Schedule
Unsynch-Comm.
Synchr.-Comm.
Software-Stack
RT and CBA
13
Wood-, glassand ceramicprocessing
machines
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Plastics
injection
molding
machines
Packaging
machines
Printing
presses
13
PROFINET Real-Time Communication
Isochronous Real-Time Communication (IRT)
PROFINET Real-Time
Communication
IRT
Factory Automation
Motion Control
Functional Scope
Requirements
RT-Communication
IRT-Communication
TimeSynchronisation
IRT-Schedule
Unsynch-Comm.
Synchr.-Comm.
100ms
10ms
<1ms
IT-Services
TCP/IP
Process data
Real-Time
Software-Stack
RT and CBA
• Requirements on Ethernet for Motion Control
14
● Highest performance
● Time synchronization inclusive determinism
● Openness for unrestricted access to the IT world,
which means no restrictions for TCP/IP
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PROFINET Real-Time Communication
PROFINET and IRT
PROFINET Real-Time
Communication
Functional Scope
What are the pre-conditions ?
Requirements
RT-Communication
IRT-Communication
TimeSynchronisation
IRT-Schedule
z Segmentation of the communication
z Use of time based communication
Unsynch-Comm.
Synchr.-Comm.
z Clock-synchronization
Software-Stack
RT and CBA
15
© PROFIBUS
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15
PROFINET Real-Time Communication
Isochronous Real-Time Ethernet
PROFINET Real-Time
Communication
• Scheduling of communication systems
Functional Scope
● High accurate cycle synchronization
Requirements
● Separate time areas for real-time and TCP/UDP
RT-Communication
IRT-Communication
TimeSynchronisation
IRT-Schedule
Unsynch-Comm.
Synchr.-Comm.
IRT
Channel
open
Channel
Cycle 1
IRT
Channel
open
Channel
Cycle 2
Cycle n
Software-Stack
RT and CBA
E.g. 1 ms position control cycle
Synchronization
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Isochronous Communication
IRT data
16
Standard Communication
e.g. TCP/IP data
16
PROFINET Real-Time Communication
Time based Communication with IRT
PROFINET Real-Time
Communication
Functional Scope
Requirements
z
Synchronized communication
z
Time based
z
No VLAN-Tag necessary
RT-Communication
IRT-Communication
TimeSynchronisation
IRT-Schedule
56 Bits
8 Bits
6 Byte 6 Byte 2 byte 2 byte
36..1490 bytes 4 byte
Unsynch-Comm.
Synchr.-Comm.
Software-Stack
RT and CBA
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Preamble SYNCH Dest
Addr
Ethertype is 0x8892
Src
Addr
Ether Frame RT.-User data
type ID
FCS
17
17
PROFINET Real-Time Communication
PROFINET and IEEE 1588
PROFINET Real-Time
Communication
Functional Scope
IEEE 1588 describes the clock synchronization
Requirements
RT-Communication
IRT-Communication
z
PROFINET is compatible to IEEE 1588
z
Æ
TimeSynchronisation
IRT-Schedule
Unsynch-Comm.
but that´s not always enough
Synchr.-Comm.
Software-Stack
RT and CBA
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Extensions to IEEE 1588 Æ better accuracy
z The Precision Time Protocol has been implemented
Æ < 1µs Jitter
18
z Exact determination of the time during send and receive
z
18
PROFINET Real-Time Communication
Principle of the Time Synchronization
PROFINET Real-Time
Communication
Sync-Master
Sync-Slave
Functional Scope
Requirements
RT-Communication
IRT-Communication
Synchronization
Sync.Req
T1
TimeSynchronisation
FollowUp.Req
T2
Terr = T2 – (T1 + Tld)
IRT-Schedule
Unsynch-Comm.
Delay.Req
Synchr.-Comm.
Software-Stack
RT and CBA
T3
Line Delay Measurement
T4
Delay.Rsp
(not every Sync -Frame )
19
Calculation line delay:
Tld = ( (T 4 – T1) – (T3 – T2) ) / 2
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19
PROFINET Real-Time Communication
Time Synchronization: Example
PROFINET Real-Time
Communication
Sync-Master
Sync-Slave
Functional Scope
Requirements
12:00
T1
Sync.Re
q
RT-Communication
TimeSynchronisation
IRT-Schedule
12:15
T3
Unsynch-Comm.
Software-Stack
12:05
FollowUp
.Req ( T1
= 12:00)
IRT-Communication
Synchr.-Comm.
ld
T2
eq
Delay.R
T4= e.g..
20 sec
RT and CBA
Delay.Rs
p (T4= 1
2:00 20)
20
12:55
1.
Calculation line delay:
Tld = ( (T 4 – T1) – (T3 – T2) ) / 2
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2. Adjust time
time in Follow up+ line delay +
local Timer from the time T2
20
PROFINET Real-Time Communication
Time Scheduling with PROFINET
PROFINET Real-Time
Communication
Functional Scope
Requirements
cycle time e.g. 1 ms
RT-Communication
green interval
IRT-Communication
red interval
reserved IRT-area
TimeSynchronisation
...
IRT-Schedule
Unsynch-Comm.
Synchr.-Comm.
Software-Stack
RT and CBA
red interval
green/red
border
green/red
border
green frame shall
complete here
21
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21
PROFINET Real-Time Communication
Behavior of Real-Time Switches
PROFINET Real-Time
Communication
RT
RT
RT
RT
NRT
NRT
Functional Scope
RT Switch
NRT Switch
Requirements
Switch
Switch
RT Phase
NRT Phase
RT Phase
NRT Phase
RT-Communication
IRT-Communication
TimeSynchronisation
NRT
RT
RT
RT
RT
NRT
IRT-Schedule
RT Switch
NRT Switch
Unsynch-Comm.
Switch
Switch
Synchr.-Comm.
Software-Stack
RT and CBA
Characteristics:
Cycle Synchronization
22
z Real-Time networks can be compared with autobahns equipped with a
passing lane, on which the NRT frames are passed by the RT frames.
z The cycle synchronization communicates the point of time to the
switches to pass through the RT frames.
z In the Real-Time phase the RT frames have “green light".
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22
PROFINET Real-Time Communication
Unsynchronized Real-Time-Communication
PROFINET Real-Time
Communication
Tsendclock
Tsendclock+1
Functional Scope
Requirements
RT-Communication
31,25ms <Tsendclock <=4ms
IRT-Communication
TimeSynchronisation
IRT-Schedule
T
T
60%
aRT
RT aRT
RT
NRT
NRT
aRT
RT aRT
RT
60%
NRT
NRT
Unsynch-Comm.
Synchr.-Comm.
Software-Stack
RT and CBA
© PROFIBUS
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RT
aRT
NRT
= Real-Time-Communication
= acyclic Real-Time-Communication (e.g.Alarms)
23
= Non-Real-Time-Communication
23
PROFINET Real-Time Communication
Unsynchronized Real-Time-Communication
PROFINET Real-Time
Communication
Functional Scope
Requirements
Tsendclock
RT-Communication
Tsendclock+1
IRT-Communication
TimeSynchronisation
31,25ms <Tsendclock <=4ms
IRT-Schedule
T
Unsynch-Comm.
Synchr.-Comm.
Software-Stack
T
60%
aRT
RT aRT
RT
NRT
NRT
60%
RT aRT
aRT
RT
NRT
NRT
RT and CBA
RT
aRT
NRT
© PROFIBUS
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24
= Real-Time-Communication
= acyclic Real-Time-Communication (e.g.Alarms)
= Non-Real-Time-Communication
24
PROFINET Real-Time Communication
Synchronized Real-Time-Communication
PROFINET Real-Time
Communication
Functional Scope
Requirements
RT-Communication
Tsendclock
Tsendclock+1
IRT-Communication
TimeSynchronisation
IRT-Schedule
Unsynch-Comm.
Synchr.-Comm.
Software-Stack
RT and CBA
© PROFIBUS
International
IRT
IRT
Time based
communication
RTaRT
aRT
RT
NRT
NRT
Address based
Communication
IRT
IRT
RTaRT
aRT
RT
NRT
NRT
25
25
PROFINET Real-Time Communication
Distribution of Refresh Times
PROFINET Real-Time
Communication
Functional Scope
Requirements
n
IRT
RT
TCP/IP
RT-Communication
IRT-Communication
TimeSynchronisation
IRT-Schedule
Unsynch-Comm.
Synchr.-Comm.
Software-Stack
RT and CBA
26
100%
15%
t
0,25...1,0
msec
© PROFIBUS
International
10
msec
100
msec
26
PROFINET Real-Time Communication
Isochronous Real-Time Communication
PROFINET Real-Time
Communication
Requirements
RT-Communication
IRT-Communication
TimeSynchronisation
IRT-Schedule
Unsynch-Comm.
Synchr.-Comm.
z
z
IT applications
e.g.
z HTTP
z SNMP
z DHCP...
PROFINET applications
Standard data
Real-Time data
TCP/UDP
IP
2
Software-Stack
RT and CBA
Ethernet
2 RT
SRT
Geräteparametrierung
Device parameterization and
Lesen
von Diagnosedaten
configuration
Laden
von
Reading
of Verschaltungen
diagnostics data
Aushandeln des
Negotiation of the communiKommunikationscation channel for user data
kanals für Nutzdaten
Real-Time
channel
2 Echtzeit
Kanal
SRT RT
z
z
z
3 IRT
Real-Time
Real-Time switch ASIC
© PROFIBUS
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z
z
z
z
1
Real-time
Functional Scope
1 Offener
TCP/IP
Kanal
Standard
channel
Performant cyclic
transfer
Performante
Übertragung
of processDaten
data
Zyklische
Ereignisgesteuerte
Event-controlled
Meldungen
signals/alarms
3 Real-Time
27
channel IRT
z
Isochronous transmission
of process data
z
Jitter <1µsec
27
PROFINET Real-Time Communication
PROFINET CBA: Real-Time between
Components
PROFINET Real-Time
Communication
• The user chooses the QoS
„Real-Time Data Transmission“ in the configuration tool
Functional Scope
Requirements
Fill
Release
Close
RT-Communication
IRT-Communication
Start
Transmission: Cyclic
Release
Start
TimeSynchronisation
IRT-Schedule
Unsynch-Comm.
Synchr.-Comm.
Software-Stack
RT and CBA
• The Communication relationships between the devices is
established over TCP/IP
• Subsequently, process data are transmitted cyclically
between devices via the Real-Time channel
28
ACCO
Establishment of
ACCO
Communication Relation
RT
Driver
© PROFIBUS
International
cyclic user data in Real-Time
RT
Driver
28
PROFINET Real-Time Communication