Synchronizing The Link Scan With The Sequence Scan (Scan Synchronous Function) - Mitsubishi MELSEC-Q Series User Manual

4 FUNCTIONS

4.4.8 Synchronizing the link scan with the sequence scan (Scan synchronous function)

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This function selects whether or not the link scan should be synchronized with the
sequence scan.
For QJ61BT11 of the function version A, it can be used only at the remote net mode.
(1) Synchronous mode
Performs data linking using the scan that is synchronized with the sequence
program.
(The sequence scan and link scan start at the same time.)
In the synchronous mode, the link scan interval becomes longer when the
sequence scan takes long because the link scan is synchronized with the
sequence scan.
IMPORTANT
While in the synchronous mode, the sequence scan time must not exceed the time
specified for the corresponding transmission rate, as listed below. If the scan time
exceeds the specified time, a time out error occurs at each station.
Transmission rate
10 Mbps
5 Mbps
2.5 Mbps
625 Mbps
156 Mbps
POINT
(1) The asynchronous mode is recommended for a mixed system of local stations
A(1S)J61BT11 and A(1S)J61QBT11 when the QJ61BT11 is used as the
master station. When using the synchronous mode, make sure to observe the
restrictions in (2) and (3) below.
(2) When using a system consisting of the QJ61BT11 as the master station in the
synchronous mode and both the A(1S)J61BT11 and A(1S)J61QBT11 as local
stations, set the sequence scan time of the local station CPU to be shorter
than ST. For more details on "ST," see Section 5.1.
(3) When using a system consisting of the QJ61BT11 as the master station in the
synchronous mode and both the A(1S)J61BT11 and A(1S)J61QBT11 as local
stations, use XnC as an interlock of the FROM/TO instructions on the local
station CPU side.
(4) When operating in the synchronous mode, the "L RUN" LED may be lit dimly.
(2) Asynchronous mode
Performs data linking without synchronizing with the sequence program.
(3) Setting method
Set the scan synchronous function in "Scan mode setting" of the network
parameters using the GX Developer. For more details on the setting, see Section
6.3.
Sequence scan time
50 ms
50 ms
100 ms
400 ms
800 ms
MELSEC-Q
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