1. Check for correct supply voltage
2. Disconnect the input connector (not the power connector).
3. Apply power to the USC701, if the power LED now remains permanently lit there is probably too much load on the "EXCIT" output for the voltage it has been programmed for, reprogram to a lower voltage or change load.

1. Switch off supply and reapply, check if unit now operates.
2. Check that suitable spike suppression is fitted across contactor coils operating from same power source.

It is possible to create equations that will lock up the USC701. The lock can occur due to an improper equation or an unhappy circumstance that occurs during programming (The equation is in use while it is being changed). To return the USC701 to operating state a short simple program is downloaded during the power up period.

1. Using the new module wizard make a signal isolator with one input one output and no relays.
2. On the "Tools" menu select "Disable Protocol Interlocks"
3. Connect the computer adaptor to the USC701 and switch off the power to the unit.
4. Press program.
5. Switch on the power to the USC701; the program should start downloading after a second.
6. If process is unsuccessful power down the USC701 and try again.
7. After the USC701 has recovered try suspect program again it may be successful or rewrite using an alternate structure.