Mitsubishi Electric MELSEC iQ-R Series User Manual page 94

Operation of the device/label access service processing
This section describes the operation of the device/label access service processing.
Ex.
When updating multiple monitor windows on the GOT
Monitoring window Ò
Monitoring window Ó
(1) From the time the CPU module sends a response until the GOT sends the next request, the CPU module will not receive requests from the GOT.
Depending on the GOT, when updating multiple monitor windows, the GOT repeats the action of sending a request (a device/
label read request) to the CPU module for each window and waiting for a request (a device/label current value).
As a result, when the windows are updated in the order of monitor window monitor window, from the time the CPU
module sends a response for monitor window  until it receives a request for monitor window  that follows, the CPU
module has no request to be processed.
When in this state, use this setting to specify whether to process a request for monitor window  in the next scan or to wait
until the set time is reached before processing in the same scan.
■Operation when this function is enabled
The following figure shows the operation when SM315 (Service processing constant wait setting flag) and SD315 (Service
processing constant wait status setting) are enabled. (Device/label access service processing setting: "Set Processing Time":
4ms)
Update
request
from
Monitoring
window Ò
Program execution
16ms
(1) Update requests from multiple monitor windows can be processed in one scan.
(2) Requests are accepted until the time set for the device/label access service processing setting is reached.
(3) The communication response is improved because requests are accepted within the device/label access service processing time.
Even after the CPU module returns a response to the GOT, subsequent requests are accepted until the time or ratio specified
for the device/label access service processing setting is reached, thereby enabling update requests from multiple monitor
windows to be processed in one scan. This improves the communication response.
In redundant mode, this function is enabled only in the CPU module of the control system in backup mode. In separate mode,
this item is enabled for the CPU modules of both systems.
8 RUNNING A PROGRAM
92
8.2 Scan Time
(1)
GOT
Update
Response
request
to
from
Monitoring
Monitoring
window Ò
window Ó
Scan time: 20ms
END processing
Other Device/label access service
processing processing
4ms
Request from Monitoring window Ò
Response to Monitoring window Ò
Request from Monitoring window Ó
Response to Monitoring window Ó
Response
to
Monitoring
window Ó
(2)
(3)
Program execution
16ms
(1)
Scan time: 20ms
END processing
Other
Device/label
processing
access service processing
4ms
END
processing
Time