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Question When I try to connect a Moxa MGate MB3180 to my serial device via 2-wire RS-485, it doesn’t work. I’ve confirmed the PIN connections are correct. What should I do next?
Question Type Installation
Updated 9/5/2017 6:01:22 PM
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To connect a serial device to a Moxa device with 2-wire RS-485, there are a few things that should be checked:
 

1. PIN assignment of Moxa device and the serial device. Moxa defines signal B as positive, and signal A as negative. Furthermore, the signal B will be PIN 3, and signal A is PIN 4 for Moxa devices with DB9 connectors.

2. Connect positive (B) pin of the Moxa Device to the positive (B) pin of the serial device, negative (A) pin of the Moxa Device to the negative (A) pin of the serial device.

 

 3. For Moxa devices that come with configuration software like drivers or firmware configuration, please check and make sure that the interface setting is set to RS-485 2w mode.

 
[Solution]
 
If you check the three factors listed above and the communication still doesn’t work, please check if your serial device is on the list below. We have found that there are some manufacturers that use a different definition than Moxa does, please swap the PIN connection to connect positive (B) pin to the negative (A) pin and try communicating again.
 
Below equipment is the list Moxa already know you should swap the PIN connection:
1. Lufft Smart Weather Sensor: WS501-UMB
2. Maxim MAX483 transceiver
3. Hawk USB Modem for communication with Hawk Sultan.
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