7922 and 7932 use an EEPROM to save the programming and count values. This is done by monitoring the internal power supply of the meter.
If the external supply voltage is switched off, the internal voltage drops accordingly and this is registered by a special circuit and the backup mechanisms are activated so that all relevant data are saved in the non-erasable memory. In addition, a so-called "checksum" is generated, which is also stored in the memory.
When the external voltage is switched on again, the processor reads the data from the memory, generates a checksum and compares it with the stored one. If the new checksum is different 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 peaks. If the error occurs due to external voltage peaks, this can be avoided by using suitable filters. To eliminate this error, a "Power Up Reset" is necessary.

1. Switch off the power supply.
2. Press the PROG key and Digit 5 key at the same time and keep them pressed.
3. Switch on the power supply again while the buttons are pressed. Keep the buttons pressed for approx. 15 seconds until 7922/7932 appears on the display.
4. The EEPROM memory is now reset to the basic values and the counter must be reprogrammed.