7 DATA COMMUNICATIONS USING BIDIRECTIONAL PROTOCOL

MELSEC-Q

7.2.2 Arrangement and contents of the transmission area and the transmission data

This section explains the arrangement and contents of the transmission area and the transmission data for performing data transmission using the bidirectional protocol. For details on the contents of transmission data, see Section 7.1.2 (3).

(1) Transmission area

The transmission area is a memory area for storing the data and the data count that are transmitted from the PLC CPU to the external device via the Q series C24. By default, the transmission area is assigned to addresses 400H to 5FFH (CH1 side) and 800H to 9FFH (CH2 side).

CH1 side

address 400H

401H

to

5FFH (Default)

Buffer memory

Transmission area

Transmission data count

designation area

 

 

Transmission data

 

designation area

 

 

• The unit of transmission data count (words/bytes) is in accordance with the word/byte units designation in GX Configurator-SC.

• Transmission data count

The transmission data count designated with the BIDOUT instruction is written, and sent as the data length.

• Transmission data

The transmission data designated with the BIDOUT instruction is written and then sent.

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