9
2.8 Serial port working state conversion
After the HLK-RM58S is powered on, the default mode is transmission mode. By pulling down
the pin ES0 (GPIO0) to enter at instruction mode longer than 50ms, the module will process the
received data as at instructions, send at instructions to let the module into transparent mode, After the
network connection, the data received by the serial port will be transmitted as transparent data.
Figure 9 Serial port mode conversion
2.9 Serial port-network data conversion
2.9.1 Module as TCP Server
Figure 10 TCP Server
In this mode, the module listens to the specified port, waits for TCP Client connection, and after the
connection, all TCP data is directly sent to the serial port end, and the data of the serial port end is sent to all TCP
Client ends. When the module is used as the TCP server, the most supporting two TCP clients are connected to the
TCP server.
AT mode
Power on
Transparent
mode
Pull down es0 pin
Send at command
TCP Server
TCP Client
TCP Client
TCP Client
