Battery Question

numbers · Nov 15, 2005

How do I change a battery on a PLC without losing the program.

Marc · Nov 15, 2005

What kind of PLC?

numbers · Nov 15, 2005

Modicom 984

Sliver · Nov 15, 2005

Thanks for reminding me, I think it's been 5 years since I have changed all the batteries on our 984-685s.
As I recall, if you leave the 120vac powered on, you can remove the battery although I can't find any documentation to prove it. The battery is to maintain the program through a power outage.

Brian.

ivo.maenen · Nov 16, 2005

I think people 'feel' the need to switch off the power before they take out the battery...but then you will lose your date...afterall the battery is there to protect this data when there is no power.

With this in mind you must be sure that you leave the power on when you change the battery. Maybe you must switch the cpu in STOP because their can be a reaction of the cpu if the battery is 'low'.

numbers · Nov 16, 2005

Thanks for the info

rdrast · Nov 16, 2005

There are some PLC's out there that you must power down in order to change the battery, some SLC's for example. In those cases, have the new battery ready and unpacked (and in your hand), kill power, pull CPU, and make the change fast.

Ones that require power down usually have a capacitor backup that will last for 1 to 3 minutes, and are usually identified by having the battery located in such a place as to require removal of a module from the backplane to change it.

In most cases though, leave power turned on to change the battery. Just like the alarm clock at home.

jstolaruk · Nov 16, 2005

How about uploading the program just before changing it? Its a little easier to recreate the program AND data tables if it goes bye-bye

Tech7 · Nov 16, 2005

Just did this myself

Yes, do not power the PLC down to change the battery on a Modicon 984. Yes, do save the program to the programming terminal, i.e. laptop first. You may leave the processor in the run state while changing the battery. The battery is located on the bottom of the CPU/Power Supply. The cap will twist out in the CCW direction and the battery will slide out. Happy trails!

Tech7

TConnolly · Nov 16, 2005

On the 984-685 you can change the battery without removing the processor or powering it down. It is advisable however to perform a read-save at this time because it is possible to modify a network in the 984-685 without saving it, and next time you go online, it will not prompt you that the offline version does not match the online file in PLC memory. So take the opportunity to refresh the offline file.

bigfoot · Nov 16, 2005

Some PLCs, one example is Omron, there are two connectors for the battery. Simply plug in the new battery before you unplug the old one.

Battery Question

numbers

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numbers

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