Omron CJ1W-DRM21 - Page 224

8 Communications Timing
8-6
CJ-series DeviceNet Units Operation Manual for NJ-series CPU Unit(W497)
N
RMMAX
is the smallest value that meets the following condition.
N
RMMAX
× T
RM
> T
RFNJ
T
RFNJ
= T
INNJMAX
+ Task period × (3 + y) + T
OUTNJMAX
y = ((Number of CPU Bus Units + 1) × 1 ms) ÷ Task period
Note Truncate the decimal portion of y and use the resulting integer in the formula.
T
INNJMAX
: Input processing time in CPU Unit (ms)
T
OUTNJMAX
: Output processing time in CPU Unit (ms)
Task period: The period of the task in which I/O refreshing is assigned for the DeviceNet Unit (ms)
Number of CPU Bus Units: The number of CPU Bus Units that are connected in the Controller
T
INNJMAX
= 0.5 + 0.0005 × Total size of all master input data in bytes
T
OUTNJMAX
= 0.2 + 0.0006 × Total size of all master output data in bytes
However, if the DeviceNet Unit is on an Expansion Rack, use the following formulas to calculate T
INNJ-
MAX
and T
OUTNJMAX
.
T
INNJMAX
= 0.5 + 0.00075 × Total size of all master input data in bytes
T
OUTNJMAX
= 0.2 + 0.0009 × Total size of all master output data in bytes
You can calculate the minimum I/O response time T
MIN
(ms) with the following formula.
T
MIN
= T
IN
+ T
RT-IN
+ T
RT-OUT
+ T
RFNJ
+ T
OUT
T
IN
: Input slave ON or OFF delay (ms)
T
RT-IN
: Communications time per slave for input slaves (ms)
T
RT-OUT
: Communications time per slave for output slaves (ms)
T
OUT
: Output slave ON or OFF delay (ms)
T
RFNJ
= T
INNJMIN
+ Task period + T
OUTNJMIN
T
INNJMIN
: Input processing time in CPU Unit (ms)
T
OUTNJMIN
: Output processing time in CPU Unit (ms)
Task period: The period of the task in which I/O refreshing is assigned for the DeviceNet Unit (ms)
T
INNJMIN
= 0.4 + 0.0004 × Data size per slave for input slaves in bytes
T
OUTNJMIN
= 0.1 + 0.0005 × Data size per slave for output slaves in bytes
However, if the DeviceNet Unit is on an Expansion Rack, use the following formulas to calculate T
IN-
NJMIN
and T
OUTNJMIN
.
T
INNJMIN
= 0.4 + 0.0006 × Data size per slave for input slaves in bytes
T
OUTNJMIN
= 0.1 + 0.00075 × Data size per slave for output slaves in bytes
Formula for the Minimum I/O Response Time