7922 and 7932 use an EEPROM to back up the programming and count values. This is done by monitoring the meter's internal power supply.
If the external supply voltage is switched off, the internal voltage drops accordingly. This is registered by a special circuit and the backup mechanisms are activated so that all relevant data is saved in the non-volatile memory. In addition, a so-called „checksum“ is generated, which is also stored in the memory.
When the external power is switched back on, the processor reads the data from the memory, generates a checksum and compares it with the stored checksum. If the new checksum differs from the previously stored one, the processor interprets this as an error and assumes that there is a data error. This results in the message „ERR CH“, which signals a data error.
This error can be caused by a defect in the processor, in the EEPROM, or by external voltage spikes. If the error is caused by external voltage spikes, it can be avoided by using suitable filters. A “power-up reset” is required to eliminate this error.

1. Switch off the power supply.
2. Press and hold the PROG button and digit 5 button simultaneously.
3. Switch the power supply back on while holding down the buttons. Hold the buttons down for approx. 15 seconds until 7922/7932 appears on the display.
4. The EEPROM memory has now been reset to its default values and the meter must be reprogrammed.