Why is my system locking up and resetting?

My weighing system occasionally locks up and/or resets by itself. What can I do to find the problem?

Review the following steps to help eliminate system reset and communication lock-up problems.

1. Verify the ground cable is connected. Also check that the shields are grounded to a single point earth ground. The Shield terminal on the back plate of your Hardy controller should be a good ground point. Verify there is single point grounding with an ohmmeter, by reading from earth ground to the shield terminal at the summing junction box (you should have one ohm or less). Then disconnect the shield wire at the back of the controller and measure from earth ground wire to the shield terminal. You should have an open reading. If there are two grounding systems, facility ground and instrument ground, verify the resistance between the two grounds are less than 1 ohm. If you are unsure if you have a proper system ground, consult an electrician for testing and ground grid diagnostics.

2. If you have conduits or piping connecting to your scale system, install grounds to the incoming product supply, vessel, and exit piping. This is to provide a path for static discharge to ground and not through the load cells or cables.

3. Load cell cables inductively pickup noise when run in the same conduit with high voltage cables. High voltage is anything over 50 volts. As a test you can isolate cable runs outside the conduit and verify operation. Re-installing the original cable runs one at a time, and testing, can help indicate which cable runs are causing a problem. The best choice is to run load sensor cables in separate conduits.

4. Cable installations with low voltage data cable trays need only separate the load sensor cables slightly. Rather than bundle all the cables together, keep separation of 2-3 inches. Properly locating load sensor cables to minimize exposure from EMI/RFI noise sources is the best way to reduce system noise.

5. If you are using a remote function connections, the cable run to the contacts can be an antenna for noise. Keep the switching cable run less than 48 inches. Use twisted pair shielded cable and route away from high voltages to reduce noise. If the remote function switch is over 48 inches away from the unit, use a relay installed close to the unit for control of the function.  Also, use a shielded twisted pair cable.

6. Power isolation, swapping displays, cards and power converters can help isolate a problem, but usually without improvement. The problems, usually, stay with the cabling and not the instrument or power.

7. Verify voltage between neutral and ground is less than one Vac. The AC voltage from line (hot) to ground should be the same as the AC voltage from line to neutral.

8. Reset your controller's memory back to factory defaults to clear any corruption in the memory. See associated WebTech answers for detailed instructions for your specific model.