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9·12
9-3 Data transfer required time and communication delay
time
(1) Required time for data transfer
This is the time required for the master station to complete communication with all stations, and is
determined by the number of connected stations with and the number of data items to transmit.
Transmission T operation cycle = + 2.5 P + + 16 (ms)
N:Total number of link points (value to be calculated by relay link bytes and register link bytes
8 points).
P:Number of connected stations (master + slave)
136 : 136 bits are used for station address and error check data on the communication format.
1250 : Transmission rate: 1.25M bits per second
2.5 : Inter-station wait time plus processing time to move to next station (unit : ms)
: Communication recovery operation time
• When an error occurs at any station, the master station periodically treats the error.
= 3.5 number of error stations ms
16 : Time to maintain token bus. It can enter at random intervals.
[Example] In the case of two connected stations and 8 bytes of link points,
Transmission T operation cycle =
+ 2.5 2 stations + 16 = 21.32 ms
N + 136 P
1250
8 bytes 8 points 2 stations + 136 2 stations
1250
Data exchange
I/O processing
Data exchange
I/O processing
Send
Slave station
(PC01)
Master station
(PC00)
PC operation
cycle
PC operation PC operation
: Receive