CHAPTER
15
AC Power
Electronic
Instrumentation and
Measurements
Measurement system
Figure 15.1
Figure
15.1
15-1
Devices for the measurement of flow
Figure 15.2
Figure
15.2
15-2
J thermocouple circuit
Figure 15.3
Figur
e 15.3
15-3
Cold junction-compensated thermocouple circuit
Figure 15.4
15-4
Figure 15.4
Effect of connection leads on RTD measurement
Figure 15.5
Figure
15.5
15-5
(a) Four-wire RTD circuit
and (b) three-wire
Wheatstone bridge RTD
circuit
Figure 15.6
15-6
Figure 15.6
Measurement system and
types of signal sources
Figure 15.7
Figure
15.7
15-7
Ground loop in ground-referenced measurement system
Figure 15.8
15-8
e
1
5.
8
Differential (nonreferenced) measurement system
Figure 15.9
Figure
15.9
15-9
Measuring signals from a floating source: (a) differential input;
(b) signal-ended input
Figure 15.10
15-10
Figure
15.10
Conductive coupling:
ground loop and
separate ground returns
Figure 15.12
Figure
15.12
15-11
Capacitive coupling and equivalent-circuit representation
Figure 15.13
Figure 15.13
15-12
Inductive coupling and equivalent-circuit representation
Figure 15.14
Figure
15.14
15-13
Shielded Cable Used to Reduce Noise
Discrete op-amp instrumentation amplifier
Figure 15.16
Figure
15.16
15-14
IC instrumentation amplifier
Figure 15.17
15-15
Figure
15.17
AD625 instrumentation amplifier
Figure 15.18
Figure 15.18
15-16
Prototype low-pass filter response
Figure 15.19
Figure
15.19
15-17
Butterworth low-pass filter frequency response
Figure 15.20
Figure 15.20
15-18
Chebyshev low-pass filter frequency response
Figure 15.21
Figure 15.21
15-19
Sallen and Key active filters
Figure 15.22
Figure
15.22
15-20
Frequency response of the low-pass filter :
Figure 15.22’
Where,
Block diagrams of a digital measuring instrument and a digital
control system
Figure 15.23
Figure 15.23
15-21
An n-bit digital-to-analog converter
Figure 15.24
Figure
15.24
15-22
A 4-bit DAC
Figure 15.25
Figure 15.24’
15-23
R-2R ladder D/A converter
Figure 15.25
A digital voltage
representation of an
analog voltage
Figure 15.26
Figure
15.26
15-24
Tracking ADC
Figure 15.27
Figure
15.27
15-25
Integrating ADC
Figure 15.28
15-26
Figure 15.28
(a) Block diagram of 8-bit successive-approximation ADC;
(b) A 3-bit flash ADC
Figure 15.29
Figure
15.29
15-27
Description of the sample-and-hold process
Figure 15.30
Figure
15.30
15-28
Sampled data
Figure 15.31
15-29
Figure 15.31
Data acquisition system
Figure 15.32
Figure
15.32
15-30
Multiplexed sampled data
Figure 15.33
15-31
Figure
15.33
Op-amp in open-loop mode
Figure 15.35
Figure 15.35
15-32
Noninverting op-amp comparator
Figure 15.36
15-33
Figure
15.36
Input and output of noninverting comparator
Figure 15.37
Figure
15.37
15-34
Input and output of inverting comparator
Figure 15.38
Figure
15.38
15-35
Comparator with offset
Figure 15.39
Figure
15.39
15-36
Waveforms of comparator with offset
Figure 15.40
Figure
15.40
15-37
Transfer characteristic of zero-crossing comparator
Figure 15.41
Figure
15.41
15-38
Transfer characteristic of
inverting comparator with
offset
Figure 15.42
15-39
Figure
15.42
Comparator response to noisy inputs
Figure 15.47
Figure
15.47
15-40
Transfer characteristic of the Schmitt trigger
Figure 15.48
Figure
15.48,
15.49
Figure
15.48
15-41
Schmitt trigger (general circuit)
Figure 15.49
15-42
Figure 15.49
Schmitt trigger response to noisy waveforms
Figure 15.50
Figure
15.50
15-43
Schmitt Trigger with Offset
Figure 15.51, 15.52
IC monostable multivibrator waveforms
Figure 15.53
Figure
15.53
15-44
Dual one-shot circuit
Figure 15.54
15-45
Figure 15.54
NE555 timer
Figure 15.55
Figure 15.
15-46
55
Figure 15.55’
Figure 15.60
GPIB System with Bus Expander
GPIB(General Purpose Interface Bus)
Figure 15.61
Description of GPIB(IEEE 488 Bus) Lines
Figure 15.61’
Figure 15.61’’
IEEE 488 (GPIB) data transmission protocol
Figure 15.62
Digital data encoded for analog transmission
Figure 15.63
Modulated digital data for mobile telecommunication
CDMA Signal
TDMA Signal
Figure 15.63’
EIA232 communication function and connector
types for a personal computer and modem. DCE
devices are sometimes called "Data
Communications Equipment" instead of Data
Circuit-terminating Equipment.
Communication of a terminal with timesharing computer using
MODEM
Figure 15.64
RS232C Communication with Modem
RS232C Communication without Modem
Format for Asynchronous Serial Data
Figure 15.64’’’
RS-232C signal names and pin numbers
Figure 15.64’
Description of RS-232 C Commonly-used Signals
Commonlyused signals
Description
Transmitted
Data (TxD)
Data sent from DTE to DCE.
Received
Data (RxD)
Data sent from DCE to DTE.
Request To
Send (RTS)
Asserted (set to 0) by DTE to prepare DCE to receive data. This may require action on
the part of the DCE, e.g. transmitting a carrier or reversing the direction of a halfduplex channel.
Ready To
Receive (RTR)
Asserted by DTE to indicate to DCE that DTE is ready to receive data. If in use, this
signal appears on the pin that would otherwise be used for Request To Send, and
the DCE assumes that RTS is always asserted.
Clear To
Send (CTS)
Asserted by DCE to acknowledge RTS and allow DTE to transmit. This signaling was
originally used with half-duplex modems and by slave terminals on multidrop lines:
The DTE would raise RTS to indicate that it had data to send, and the modem would
raise CTS to indicate that transmission was possible.
Commonlyused signals
Description
Data Terminal
Ready (DTR)
Asserted by DTE to indicate that it is ready to be connected. If the DCE is a modem, this
may "wake up" the modem, bringing it out of a power saving mode. This behaviour is
seen quite often in modern PSTN and GSM modems. When this signal is de-asserted, the
modem may return to its standby mode, immediately hanging up any calls in progress.
Data Set
Ready (DSR)
Asserted by DCE to indicate the DCE is powered on and is ready to receive commands or
data for transmission from the DTE. For example, if the DCE is a modem, DSR is asserted
as soon as the modem is ready to receive dialing or other commands; DSR is not depend
ent on the connection to the remote DCE (see Data Carrier Detect for that function). If
the DCE is not a modem (e.g. a null modem cable or other equipment), this signal should
be permanently asserted (set to 0), possibly by a jumper to another signal.
Data Carrier
Detect (DCD)
Asserted by DCE when a connection has been established with remote equipment.
Ring Indicator
(RI)
Asserted by DCE when it detects a ring signal from the telephone line.
Figure 15.64’’
USB (Universal Serial Bus)
Figure 15.66
USB 2.0 PCI Controller
Figure 15.67
Computer Networks
Figure 15.65
Concept of Internet Protocol Layer
TCP/IP stack operating on two hosts connected via two
routers and the corresponding layers used at each hop
Encapsulation of application data
descending through the protocol stack.
CAN bus line and Frame of CAN message
Figure 15.65
Frame format of CAN
Figure 15.65’
* Identifier field is composed by 4bits function code and 7 bits node-id by CANopen protocol.
Communication objects
Length
Function code
Node ID
RTR
Data length
4 bits
7 bits
1 bit
4 bits
Data
0-8 bytes
Service Data Object (SDO) protocol
3 bits
1 bit
ccs=1
reserved(=0)
2 bits
1 bit
1 bit
2 bytes
n
e
s
index
1 byte
subindex
4 bytes
data
ccs is the client command specifier of the SDO transfer, this is 0 for SDO segment
download, 1 for initiating download, 2 for initiating upload, 3 for SDO segment upload
and 4 for aborting an SDO transfer
n is the number of bytes in the data part of the message which do not contain data, only
valid if e and s are set
e, if set, indicates an expedited transfer , i.e. all data exchanged are contained within the
message. If this bit is cleared then the message is a segmented transfer where the data does
not fit into one message and multiple messages are used.
s, if set, indicates that the date set size is specified in n (if e is set) or in the data part of the
message
index is the object directory index of the data to be accessed
subindex is the subindex of the object directory variable
data contains the data to be uploaded in the case of an expedited transfer (e is set), or the
size of the data to be uploaded (s is set, e is not set)
Process Data Object (PDO) protocol