I/O Response Time In Asynchronous Mode - Omron C200HW-PRM21 Operation Manuals

Performance

3-2-3 I/O response time in asynchronous mode

Minimum I/O response time
Conditions
In asynchronous data transfer mode, the fieldbus cycle is not synchronised
with the PLC cycle; fieldbus cycles are triggered continuously, independent of
the PLC cycle.
The figure below shows the minimum I/O response time in asynchronous
mode. The figure shows the timing at the PLC, the timing at the Master Unit,
the timing at the slave input and the timing at the slave output.
t : The Input Slave's ON (OFF) delay
IN
t : The Output Slave's ON (OFF) delay
OUT
t : The fieldbus cycle time
BC
t : The I/O refresh time
RF
t : Program Execution time
PE
The minimum response time can be achieved under the following conditions:
1. No other master is connected to the network. More masters will increase
the fieldbus cycle time due to the token rotation between masters.
2. User defined I/O data mapping. Only map the input and output data of the
configured slaves. This will minimise the number of words that needs to be
transferred per PLC cycle and therefore the I/O refresh time.
3. The fieldbus baud rate is set to the highest value allowed for the attached
slaves and the used cable length.
4. The IORF instruction can be used to further decrease processing time in
the PLC program.
The minimum I/O response time that can be achieved with C200HE, -HG or -
HX and the CS1-series is approximately
9 ms + t + t
IN OUT
Section 3-2
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