4-6. Communication Times
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Time for P/W PC Link Processing at Each Station
The time needed for P/W PC Link Processing at a station in PC Link Mode is calculated using the following
equation :
Time for Data Transfer Processing at Each Station
The time needed for Data Transfer processing at a station is calculated using the following equations :
1) When the Data Transfer function is not performed
Tdti = 0 ms
2) When the Data Transfer function is performed at station i
Tdti = 1.0 ms + 0.04 ms x Bdti + Tadi
where :
Bdti = Number of bytes needed for the Data Transfer instruction.
One instruction consists of one command and one response message.
The number of bytes for each message is calculated as :
1. F145(P145) Command Message
6 bytes + (Number of data sent) x 2
2. F145(P145) Response Message
3 bytes
3. F146(P146) Command Message
7 bytes
4. F146(P146) Response Message
3 bytes + (Number of data received) x 2
Tadi = Time additionally needed for the Data Transfer operation when the station is in PC Link Mode.
1. When the station is not in PC Link Mode
Tadi = 0 ms
2. When the station is in PC Link Mode
Tadi = 1.0 ms
1) When the station is not in PC Link Mode
Tpci = 0 ms
2) When the station is in PC Link Mode
Tpci = 1.0 ms + 0.04 ms x Bpci
where :
Bpci = Number of bytes(= 8 bits, = 1/2 word) used for the send relay & data link areas in
station i(UNIT NO. i).
[number of bytes used for send relay link area = points/8(= words x 2)]
[number of bytes used for send data link area = words x 2]
