Replacing 1756-L61S ControlLogix Battery

zacslade

Member
Join Date
Oct 2014
Location
Phoenix, AZ
Posts
84
Hi all,

It's my understanding that the ControlLogix battery protects persistent memory when the device is powered off. So, the device can continue to run normally after the battery fails until it is powered off. Is that right? Does the battery do anything else?

Also, if a 1756-L61S controller has a bad battery, do I have to power it down and take it out of the chassis to replace the battery? Or is it possible to change the battery while the controller is online?

Thanks!
 
It's always a good practice to go online and save the program to the pc.
then save the program to the pc and this time include the data parameters.

that way, if you loose power and the program while you are changing out the battery, you have a good restoration point.

Remember, the program in the plc is the master! what is on paper or on the pc can and most likely is out of date. Someone always makes changes and forgets to tell others or put the changes onto the network drive.

james
 
Does the battery do anything else?

It holds up the volatile RAM (the User Program) and runs the Real Time Clock.

On the 1756-L6x controllers, they will lose the program immediately if powered down with a low/dead/missing battery. There is no capacitor that holds the memory for a few hours or days like there is on the SLC-500.

The 1756-L6x Series A had a battery that was mounted on the board and you have to remove the CPU from its slot to replace the battery. The Series B controllers moved the battery to the front.

I don't know if the Safety versions of the 1756-L6x were all Series B or not. You can tell quickly just be opening the front door of the CPU and looking for the blue-jacketed battery and the CompactFlash slot. On Series A, those were internal (battery) and on the bottom (CF) and were not accessible without removing the module from the chassis.

You can disconnect and replace the battery on a Series B controller while powered up and in RUN mode; the BAT LED will switch off a few seconds after you connect the fresh battery.
 
Good info, guys! Thanks for the help! I've confirmed that it's a series B controller. It's good to know that I can replace it while in run -- I'll see if I can get a moment of downtime, just in case, though.

Thanks again!
 

Similar Topics

Good afternoon, Guys: we use 1756-L71S and L7SP together, we want to replace 1756-L71S with new L72S, at first we need to assign IP address to...
Replies
5
Views
1,527
Are there any concerns I have to worry about when replacing a 1756-CNB/D with a 1756-CN2 card? I have a customer who is currently getting close...
Replies
3
Views
3,503
I have a plc @-20 in my factory where i cannot anymore upload the ladder program . . I Have in front of me a plc 2-30 .. Can i replace it ...
Replies
1
Views
84
After replacing the 70 with the 525, the PLC can read from the drive and recognizes it as online, but no commands are being listened to. PLC is...
Replies
1
Views
494
Hello all, It's been a while but have an odd request. Have a customer that has a AB SLC5/05 with a SDN module. On the network are several...
Replies
3
Views
1,126
Back
Top Bottom