
B-62924EN/04 OPERATION 1.16i/18i/21i-A/B, Power Mate i-D/H, AND 16/18-C
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1.2.5 Updating DI/DO Data for the Master Function
When creating a ladder program, fully consider the data refresh time
and data simultaneity described below.
Data refresh time
The data refresh time for the master function means the time required
for updating DI/DO data for all slave stations that is allocated in the R
area of the PMC by address assignment.
NOTE
DI/DO data only for the slave stations for which
ENABLE is set as a slave parameter is to be
updated.
In this section, a slave station for which ENABLE is
set is described as a communication slave station.
When only the master function is used
The data refresh time for the master function is indicated by
REFRESH TIME on Screen 1-2. When REFRESH TIME : X MSEC
[Y + Z] is assumed, the meaning of each item is as follows:
X: Data refresh time (= Y + Z)
Y: One-scan time within the communication board (msec)
Z: One-scan time within the CNC (msec)
The one-scan time indicates the DI/DO processing time for all
communication slave stations.
The number of digits that can be displayed is 3 for X, 3 for Y, and 4
for Z. If the number of digits is exceeded, OVR or OVER is displayed,
and it does not affect communication.
CAUTION
Note that DI/DO data may not be updated within the
time displayed for REFRESH TIME in either of the
following cases:
- The status of at least one communication slave
station is changing every moment.
(In this case, diagnose data must be updated.)
- A service is being received from a class-2 master
station every moment.
Y: The one-scan time within the communication board depends
greatly on the bus parameter setting. When the baud rate is 12
Mbps and normal communication is performed with all slave
stations, however, the value of Y is 8 msec in most cases.