20 SERIAL COMMUNICATION INSTRUCTIONS
20.1 Sending Data Using the On-Demand Function
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• By using the on-demand function of MC protocol of the module specified by (U), the data stored in the device specified by
(s2) and later is sent according to the control data in the device specified by (s1) and later.
• The completion status of the G(P).ONDEMAND instruction can be checked with the completion device (d) and the
completion status indication device (d)+1.
• The following figure shows how the G(P).ONDEMAND instruction operates when completing its execution.
• The following table summarizes the processes that take place if another instruction is issued while the G(P).ONDEMAND
instruction is active or the G(P).ONDEMAND instruction is issued while another instruction is active with the same channel.
*2 The following instructions are not available with the same channel as for the G(P).ONDEMAND instruction because they use a
communication protocol different from the one used by this instruction. In addition, if these are used with the same channel as for the
G(P).ONDEMAND instruction, a communication protocol setting error (7FF2H) will occur. (except for the Z.BUFRCVS instruction).
• The local device and the file register for each program are not available for setting data.
CH: Channel
• Completion device (d)
This device turns on during END processing of the scan where the G(P).ONDEMAND instruction completes, and turns off during the next END processing.
• Completion status indication device (d)+1
This device turns on or off depending on the completion status of the G(P).ONDEMAND instruction.
When completed successfully: The device remains off.
When completed with an error: The device turns on during END processing of the scan where the G(P).ONDEMAND instruction completes, and turns off during
the next END processing.
Instruction to execute
concurrently
*2
Possibility of
concurrent execution
Handling for concurrent execution
G(P).ONDEMAND The instruction is ignored and does not start processing until the active instruction completes.
Concurrent execution is, however, possible if they use different channels.
ZP.CSET A dedicated instruction concurrent execution error (7FF0H) occurs in the second instruction.
Concurrent execution is, however, possible if they use different channels.
G(P).PUTE
G(P).GETE
G(P).SPBUSY
ZP.UINI A dedicated instruction concurrent execution error (7FF0H) occurs in the second instruction.
• G(P).CPRTCL, G(P).OUTPUT, G.INPUT, G(P).BIDOUT, Z.BUFRCVS, and G(P).PRR instructions
(s1)
b15 b0
CH1
CH2
CPU module Serial communication module
…
END0 0 END0ENDEND 0 END0
OFF
OFF
OFF
OFF
ON
ON
Sequence scan
G(P).ONDEMAND
instruction
Completion device (d)
1 scan
Completion of
the instruction
Completed successfully
Completed with an error
Execution of the instruction
Completion status
indication device (d)+1
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