Why does CM11A have batteries in it?

[Deane Johnson]

I took my CM11A off the shelf today to do some updating of my PCS switches and it wouldn't work. Discovered batteries that were totally dead. Replaced them and it worked like a charm.

Now I'm curious. Why does a device that plugs into the AC need batteries? What do they do? What runs them down? How long does it take?

Anyone with ideas on this.

Thanks

Deane

 

[JeffCharger]

I believe that the batteries are only used when the device is not powered, to retain the internal clock. When connected to an automation system it will be sycronized with the PC clock. During operation, there is no reason for batteries.

 

[BLH]

I believe the batteries also kept any downloaded times and macros safe in a power loss.
When first powered up the CM11A may have been trying to send a request for clock set command.

 

[JeffCharger]

A number of years ago I went through a lengthy investigation on the CM11a. It apparently doesn't use the batteries for anything other that the clock in a power failure. The commands are kept in eeprom so don't require the battery. I have one that's been running for about 7 years this way with macros downloaded.