Chapter 14 On-Demand Data Communications Using User Frames; Data Communication Function Using User Frame - Mitsubishi Electric MELSEC iQ-R Series User Manual

14
ON-DEMAND DATA COMMUNICATIONS USING
USER FRAMES
During communications between a target device and a CPU module using the MC protocol, on-demand data can be
transmitted from the CPU module to the target device with the on-demand function using user frames.
This chapter explains the transmission of the data specified by the CPU module using a message format other than the
formats ( 1C frame format 1 to 4, 4C frame format 5) described in the following manual.
( MELSEC Communication Protocol Reference Manual)
14.1

Data Communication Function Using User Frame

The data communication using user frame means transmitting/receiving the first and last parts of a message in the format
selected by a user in data communications between the CPU module and target devices via C24.
By using the function described in this chapter, on-demand data in the order shown below can be transmitted from C24 to the
target device.
Ex.
Transmitting data according to the order of 3C frame, format 1
On-demand data
H L H L H L H L H L
Transmitted by user frame.
Data can be communicated using the user frames by registering in advance (by data codes) message formats that can be
transmitted/received by the target device according to its specifications as user frames in C24.
In the above figure, C24 transmits the on-demand data as described below:
• Sum check code of a user frame
C24 calculates the sum check code according to the contents registered in advance by the user, and transmits it as ASCII/
binary data.
• Other than sum check code of a user frame
C24 transmits data of the code registered in advance by the user. (No conversion)
• Send data (character B portion)
This is the data that the program requested to transmit with ONDEMAND instruction.
It is transmitted with the same contents and in the same order as the one transmitted without using a user frame according
to the communication protocol and word/byte designation by the parameters of Engineering tool. ( MELSEC
Communication Protocol Reference Manual)
As shown in the left, the user can sort the data
except for the "Send data" portion.
character
area
H L
14 ON-DEMAND DATA COMMUNICATIONS USING USER FRAMES
14.1 Data Communication Function Using User Frame
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