Omron CJ1W-DRM21, Operation Manual

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8-5
8 Communications Timing
CJ-series DeviceNet Units Operation Manual for NJ-series CPU Unit(W497)
8-1 Remo
te I/
O Co
mm
u
n
ication
s Characteristics
8
8-1
-2 Calculating Guidelines f
or I/
O Re
sponse T
imes
This section describes the formulas to use to calculate the minimum and maximum I/O response times
for the following configuration. Refer to
8-1-1 Communications Cycle Time for the communications cycle
time and the communications time per slave, which are used in the formulas.
Precautions for Safe Use
Actual I/O response times depend on the number of CJ-series Units that you use, the size of I/O
data that is refreshed for other CPU Bus Units, and other factors. The values that are calculated
with these formulas are guidelines only. You must always check performance under actual condi-
tions with the actual hardware and make sure that suitable I/O response times are achieved.
You can calculate the maximum I/O response time T
MAX
(ms) with the following formula.
T
MAX
= T
IN
+ T
RM
×
2 + N
RMMAX
×
T
RM
+ T
RT-OUT
+ T
OUT
T
IN
: Input slave ON or OFF delay (ms)
T
RM
: Communications cycle time (ms)
N
RMMAX
: Number of communications cycles of the DeviceNet Unit that waits for data to return from the
CPU Unit
T
RT-OUT
: Communications time per slave for output slaves (ms)
T
OUT
: Output slave ON or OFF delay (ms)
8-1-2 Calculating Guidelines for I/O Response Times
Formula for the Maximum I/O Response Time
DeviceNet
Input slave
Output slave
NJ-series CPU Unit
I/O response time
DeviceNet
IN1 OUT1
IN1
OUT1
IN1
OUT1
User program