7 DATA COMMUNICATIONS USING BIDIRECTIONAL PROTOCOL

MELSEC-Q

(b)Data length

This indicates the number of bytes or words for the data portion of the message.

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

1)For data communication from the external device to the Q series C24 The Q series C24 checks the length of the data received.

When the reception is normal, the Q series C24 stores the receive data in the receive data storage area of the Q series C24 buffer memory, assigning the first byte as the lower byte (L).

2)For data communication from the Q series C24 to the external device The length of the transmission data is the number of the transmission data designated by the sequence program using the BIDOUT instruction.

The Q series C24 sends this value as is from the lower byte (L).

(c)Data portion

This consists of an array of original one-byte data to be transmitted to the external device side, which can handle 00H to FFH code data.

1)For data communication from the external device to the Q series C24 If the receive data portion is normal, the Q series C24 takes the codes as is and stores them in the receive data storage area in sequence, beginning with the youngest address.

The storage size is in accordance with the data length in the message (See item (b) above) and the word/byte units designation in GX Configurator-SC.

2)For data communication from the Q series C24 to the external device The transmission data portion is the number of the transmission data designated by the sequence program using the BIDOUT instruction.

The Q series C24 sends the transmission data using the existing codes until the transmission data count is reached in accordance with the word/byte units designation in GX Configurator-SC to the transmission data designation area.

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