Mitsubishi QJ71MB91, User Manual

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10
DEDICATED INSTRUCTIONS
10.2 Z(P).MBRW
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(3) Function
The following explains the functions of the MBRW instruction.
(a) Processing details
MODBUS device data are read from or written to the slave specified by the
target station number of the control data.
Processing by the automatic communication function can be performed from a
sequence program at any given timing.
(b) Number of simultaneously executable instructions
The number of simultaneously executable dedicated instructions is one instruction
per channel.
Create a sequence program so that the number of dedicated instructions to be
simultaneously executed will not exceed the limit.
Failure to do so may cause the following:
1) When execution of two or more MBRW instructions are attempted:
The executed instructions are ignored.
2) When the MBRW instruction execution is attempted during execution of the
MBREQ or UINI instruction:
An error occurs when the MBRW instruction is executed.
(c) Frame mode setting
The frame mode (RTU mode/ASCII mode) is set with the intelligent function
module switch. (
Section 6.6)
(d) Start, Address, Error check and END fields of the protocol data unit
The QJ71MB91 automatically enters values in Start, Address, Error check and
END fields of the protocol data unit.(
Section 4.2.1)
(e) Data to be stored in read/write data storage devices
Data are stored in RTU format (binary) regardless of the frame mode (RTU mode/
ASCII mode).