Brother MELSEC iQ-F TD-4420TN Program Reference Manual page 24

6.1.3.2. Transmission processing
The data is transmitted with the number of bytes which is shown in the transmit data length wTransDataSize
stored in wSendData [ ].
For the operation of M+FX5UCPU-SerialComm_Output, refer to "MELSEC iQ-F FX5 CPU Module Function
Block Reference" for the Mitsubishi Electric programmable controller.
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MELSEC iQ-R Brother Label Printer Sample Program Reference Manual