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Figure 15.6(a) Four-wire RTD circuit and (b) three-wire Wheatstone bridge RTD circuit
Figure 15.6
15-6
Measuring signals from a floating source: (a) differential input; (b) signal-ended input
Figure 15.10
Figure 15.1015-10
Figure 15.23
Block diagrams of a digital measuring instrument and a digital control systemFigure 15.23
15-21
Figure 15.29
(a) Block diagram of 8-bit successive-approximation ADC; (b) A 3-bit flash ADCFigure 15.29
15-27
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.
Figure 15.63’
Figure 15.64
Communication of a terminal with timesharing computer using MODEM
RS232C Communication with Modem RS232C Communication without Modem
Format for Asynchronous Serial Data
Commonly-used signals
Description
Transmitted Data (TxD)
Data sent from DTE to DCE.
Received Data (RxD)
Data sent from DCE to DTE.
Request ToSend (RTS)
Asserted (set to 0) by DTE to prepare DCE to receive data. This may require action onthe part of the DCE, e.g. transmitting a carrier or reversing the direction of a half-duplex channel.
Ready ToReceive (RTR)
Asserted by DTE to indicate to DCE that DTE is ready to receive data. If in use, thissignal appears on the pin that would otherwise be used for Request To Send, andthe DCE assumes that RTS is always asserted.
Clear ToSend (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.
Description of RS-232 C Commonly-used Signals
Commonly-used 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 dependent 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.
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.
Concept of Internet Protocol Layer
Figure 15.65’
Frame format of CAN
* Identifier field is composed by 4bits function code and 7 bits node-id by CANopen protocol.
3 bits
1 bit2
bits1
bit1
bit2
bytes1 byte
4 bytes
ccs=1
reserved(=0)
n e s indexsubindex
data
Function code
Node ID
RTR
Data length
Data
Length
4 bits 7 bits1 bit
4 bits 0-8 bytes
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)
Service Data Object (SDO) protocol
Communication objects
Process Data Object (PDO) protocol