Interlock Program Example - Mitsubishi Electric Melsec QJ71LP21 Reference Manual

6 PROGRAMMING

6.2.3 Interlock program example

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When data larger than two words (32 bits) are transferred at one time with the 32-bit
data assurance function or the station-based block data assurance function disabled,
old and new data may be mixed in units of one word (16 bits).
As in the example below, provide interlocks in a program using the oldest number of
either the link relay (B).
1) The send command turns on.
2) The contents of D0 to D2 are stored in W0 to W2.
3) Upon completion of storage in W0 to W2, B0 for handshaking turns
on.
4) By cyclic transmission, the link relay (B) is sent after the link register
(W), which turns on B0 of the receiving station.
5) The contents of W0 to W2 are stored in D100 to D102.
6) Upon completion of storage in D100 to D102, B100 for handshaking
turns on.
7) When the data is transmitted to the receiving station, B0 turns off.
POINT
This interlock program example is not usable in the MELSECNET/H Extended
mode. Use the station-based block data assurance.
MELSEC-Q
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