I/O Response Time - Omron CQM1-ARM21 Operation Manual

Performance

3-3-3 I/O Response Time

Minimum I/O response time
The fieldbus cycle is not synchronised with the PLC cycle; fieldbus cycles are
executed continuously, independent of the PLC cycle.
The figure below illustrates the minimum I/O response time. Shown are the
timing at the PLC CPU, the AS-Interface bus, the Master Unit, the slave input
and the slave output.
CPU
Master
Bus t
BC1
Input t
IN
Output
t : Input Slave's ON (OFF) delay.
IN
Physical signal change at the terminals → data available for trans-
mission.
t : Bus cycle delay. Minimal if the slave input data changed just before
BC1
being seviced.
t : Master processing time.
MP1
Start receiving slave response → data available at the I/O bus.
t : I/O refresh time.
RF
Time required to update inputs and outputs of all CQM1 I/O units.
t : Program Execution time
PE
Processing of the PLC program and peripherals
t : PLC Cycle time (scan time) = t
PLC
t : Master processing time.
MP2
Data available at the I/O bus interface → ODI updated.
t : Bus cycle delay. Minimal if the ODI was updated just before the
BC1
master sevices the output slave.
t : Output Slave's ON (OFF) delay.
OUT
Data received from master → physical signal change at the termi-
nals.
t = t + 2* (t + t
RESPONSE IN BCx
in which t and t
IN
using a programming console or by monitoring AR27 in the CPU.
The minimum value of (t
for one data exchange, i.e. 154 µs.
t
PLC
t t
RF PE
t
MP1
t
RESPONSE
+ t
PE RF
)+ t + t
MPx PLC OUT
are slave dependent, and t
OUT
+ t ) is approximately the time required
BCx MPx
Section 3-3
t
RF
t
MP2
t
BC2
t
OUT
can be determined
PLC
21