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

1. Switch off the power supply.
2. Press and hold the PROG button and Digit 5 button at the same time.
3. Switch on the power supply again with the buttons 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 default values and the counter must be reprogrammed.