Omron CS1W-SLK11-21 - 06-2004, Manual

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66
Data Link Characteristics Section 4-11
Scan Time for PLC 1
Taken to be 25 ms in this example.
Scan Time for PLC 7
Taken to be 10 ms in this example.
Maximum Data Link I/O Response Time
The following delays occur at 1, 2, and 3 in the above diagram:
1,2,3... 1. The input bit turns ON just after a scan and so the time required for one
more scan elapses before the input is processed. Therefore a multiplica-
tion factor of 2 is applied to the scan time, as shown in the above table.
2. Processing for the input data is exchanged immediately after the right to
transmit is transferred from PLC 1, and so the time required for communi-
cations is extended by approximately one communications cycle. There-
fore a multiplication factor of 2 is applied to the communications cycle time,
as shown in the above table.
3. Data is exchanged data with PLC 7 just after one scan and so the time re-
quired for one more scan elapses before output processing is performed.
Therefore a multiplication factor of 2 is applied to the scan time, as shown
in the above table.
Note (a) A multiplication factor of 3 (not 2) is applied to the scan time for
PLC 7 if it is longer than the communications cycle time.
(b) The I/O response time will also be affected by noise and other fac-
tors.
Input ON response time 1.5 ms
Scan time for PLC 1
×
2 25 ms
×
2
Communications cycle time
×
2 19 ms
×
2
Scan time for PLC 7
×
2 (see note a) below) 10 ms
×
2
Output ON response time 15 ms
Total (data link I/O response time) 124.5 ms
Input
Instruction
execution
I/O processing
Data exchange
Scan time for PLC 1
Communications cycle
Scan time for PLC 7
Output
Instruction execution
Instruction
execution
(1)
(2)
(3)