GetSetModbusData.srv

# unsigned char data to be sent to tool device through modbus
uint8[] send_data

# Specify the anticipated maximum respond data length in bytes
int16 respond_len

# host id, 9: END RS485, 10: Controller RS485
uint8 host_id

# whether to choose transparent transmission
bool is_transparent_transmission

# whether to use port 503 for communication
# if it is true, it will connect to 503 port for communication when it is used for the first time, which is generally only useful for transparent transmission
bool use_503_port

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int16 ret
string message
uint8[] respond_data