USB-COMi RS-485 Connection Diagram

Troubleshooting:  

The diagram above is intended to cover as many different host RS-485 serial port designators as possible. The Data line on every DGH module is RS-485 data positive (+) line and the Data* line is data minus (-). Use the following list to further assist with RS-485 communications problems.

1. Using a voltmeter, measure the power supply voltage at the +Vs and GND terminals to verify the power supply voltage is between +10 and +30Vdc. 
  
2. Verify using an ohmmeter that there are no breaks in the communications data lines. 
  
3. Confirm software communications settings in Host computer match those values being used by the connected module(s). 
  
4. If the Baud Rate value being used in the application is greater than 300 Baud and the module will only communicate 300 Baud then make sure that the DEFAULT* terminal is not connected to Ground (GND). 
  
5. If the problem is not corrected after completing the steps above then connect the module by itself to a Host computer as outlined in Chapter 1.0 under "Quick Hook-up". Start the supplied Utility software and please call the factory for further assistance.