Omega A2400 manual Chapter Troubleshooting, Symptom RS-232 Module is not responding to commands

Chapter 8

Troubleshooting

Symptom: RS-232 Module is not responding to commands

1Using a voltmeter, measure the power supply voltage at the +Vs and GND terminals to verify the power supply voltage is between +10 and +30Vdc.

2Verify using an ohmmeter that there are no breaks in the communica- tions data lines.

3Connect the module to the host computer and power-up each device (module and computer) then using a voltmeter measure the voltage be- tween RECEIVE and GND. This voltage should be approximately - 10Vdc. Repeat the measurement between TRANSMIT and GND terminals and confirm the voltage value to be approximately -10Vdc. If either of the two readings is approximately 0.0Vdc then the communications data lines are wired backwards. Proper communications levels on both TRANSMIT and RECEIVE terminals should idle at -10Vdc.

4If you are using a serial communications converter (A1000) ensure that the communications Baud Rate switch is set to the proper Baud Rate value.

5Confirm software communications settings in Host computer match those values being used by the connected module(s).

6If 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).

7If the module(s) are being used in a RS-232 daisy-chain communica- tions configuration then ensure that the “Echo Bit” is enabled in the setup(SU) message of each module.

8If 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.

Symptom: RS-485 Module is not responding to commands

1 Perform steps 1, 2, 4, 5 and 6 listed above.