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MELSEC-Q
9 DEDICATED INSTRUCTIONS
9
9 DEDICATED INSTRUCTIONS
Dedicated instructions are used to simplify programming when using intelligent function
module functions.
This chapter describes the dedicated instructions for the Q series C24, which is part of
the functions of the QCPU (in Q mode) explained in this manual.
9.1 Dedicated Instruction List
The following table lists the dedicated instructions explained in this chapter.
Application
Dedicated
instruction
Description of function
Explanation
page
On-demand function transmission ONDEMAND
Sends data using the on-demand function of the MC
protocol.
Section 9.2
OUTPUT Sends data for the specified data count. Section 9.3
Non procedure protocol
communication
INPUT Reads received data. Section 9.4
BIDOUT Sends data for the designated data count. Section 9.5
Bidirectional protocol
communication
BIDIN Reads received data. Section 9.6
Communication status confirmation SPBUSY
Reads the status of data transmission/reception via a
dedicated instruction.
Section 9.7
Receive data clear CSET
Perform the receive data clear without stopping the
transmission processing during the non procedure
protocol.
Section 9.8
POINT
(1) The user should not change data values (control data, request data, etc.)
designated by a dedicated instruction until the execution of the dedicated
instruction is completed.
(2) Dedicated instructions for the Q series C24 are executed based on the current
setting values stored in the buffer memory when the module is started.
When it is necessary to change a setting value, change the value by GX
Configurator-SC before starting up the module.
Alternatively, a setting value can be changed via the sequence program using
a CSET instruction before starting up the PLC CPU (See the User's Manual
(Application)).
1) Area of buffer memory assigned as applicable functions for dedicated
instructions.
2) Setting values for data communication
• Word/byte units designation
• Receive complete code
• Received data count
etc.