PLC battery hot-swap

Folks,
We have a black-box provided by a vendor that we maintain. Inside the box, there is a Modicon TSX Micro 3722 PLC. On the front panel of that PLC, there is a battery compartment door. Inside the door, is the battery that maintains the PLC memory if the power fails. We have literature on the unit that indicates the battery should be replaced yearly. None of the literature we have indicates whether we can hot-swap the old battery with the new one. We have looked on-line and also looked on the Telemecanique website (www.telemecanique.com)and have found nothing.

Can someone help? Does anyone know if you can hot-swap the memory protect battery in the Modicon TSX Micro 3722 PLC??

Thanks for help!

The battery is intended to be hot swapped. If you turn off the power and then remove the battery, what would maintain your program?

Not sure if this might help, or it's applicable to your situation, but...

I had an AutomationDirect 260 CPU that had a slide-out door for the 3v coin cell battery - probably similar to yours. It was in a hard to get to location, and since the machine was powered down for long periods, the battery would go flat fairly quickly. With the DL260, the program was saved to FLASH, so it remained intact, but any and all variables in memory disappeared. Mighty annoying for the operator on power-up.

I mounted a 3/32" phono jack through the front of the CPU, and rewired the leads from the battery holder to it. A male plug connected to that jack, and ran to an easily accessible battery holder with two D-cells. The batteries last FOREVER, are really cheap to replace, and are in a much easier to get to location - no more unplugging terminal blocks to get at the battery.

See the atttached pic for details. I hope this helps!



PS Yes, that is 22ga stereo wire solder-spliced and heat shrunk to the battery holder leads. It fit the 3/32" male plug perfectly. I figured even stereo wire was good for 3v

rpoet

Most plc's have a large enough capacitor so if you remove the battery it gives you 10 - 30 mins to replace the battery, however this might not always be the case.
Some plc manufacturers recommend you remove power then replace the battery, however I have replaced many (hundreds) of batteries on siemens, Ab, mitsi etc. with the power on, never once have I corrupted the program or data, nor has it caused any glitch that affected any outputs, on some you need to power down then up after the battery replacement to clear the batt error led, although in general this will not affect anything & can be done when convienient.
Also most plc's will not need the battery changing for 3-5 years if powered up most of the time, but it makes sense to change at least once a year.
I once had an A series mitsi where we replaced the processor & re-loaded a new program (keeping the original as backup) when all commissioning was done we removed the battery & it was left for about 8 days, we fitted the processor to our test rack to do some mods & test before going to site & hey presto the original program & data was still intact.

Thanks for the help!!

Folks,

Thank you for the replies, they were quite reassuring. Given that we tend to be paranoid types, we also contacted the original vendor of our black box (ie the vendor who integrated the Modicon TSX Micro 3722 PLC into the hardware we purchased). Just this morning, we received an email from one of their engineers that confirms we can hot-swap the batteries in this unit.

We plan on doing this in a week or so and will post whether we had any issues.



Once again, thanks for your help!

Did I need to mention that I worked with TSX plcs for 5+ years? Their batteries are intended to be replaced with the power applied.