GE 90-30, CPU 363, plan for logic equal for today's service call.

[AutomationTechBrian]

I have a customer who has a 90-30 on a Ferry Rotomold machine. I've worked with him before to troubleshoot some issues. I uploaded the file from the PLC to my Profacy Machine Edition, but couldn't get logic equal to go live. I hesitate downloading the program I uploaded because I don't have a backup plan if something goes wrong.... until now.

He bought a refurbished CPU 363 that matched firmware with the current CPU. I'm going there today to remove the old CPU, set it aside, and install and download the file to the replacement CPU.

I'm still a rookie with the GE PLCs. Are there any little "gotchas" that I should know about? I think one that I remember... upload *everything* when I'm making the selection, right?

On the phone he said the current CPU is "blowing fuses". Not sure how PLC literate he is, and whether he's using the right terminology. He makes it sound like the CPU card is blowing fuses. Does that make sense?

 

[Steve Bailey]

Are there any little "gotchas" that I should know about?
I'm going there today to remove the old CPU, set it aside

The battery that backs up the CPU's RAM memory is located on the power supply module. If you remove the existing CPU and set it aside for more than 20 minutes or so, you risk losing its memory. There is a place to connect a battery directly to the CPU module. Remove the front cover and it is between the keyswitch and the LEDs.
The "PLC blowing fuses" sounds like an overload in an output circuit, although there is a fuse on the power supply module. You have to remove the front cover of the power supply to get at it.
Definitely upload everything from the existing PLC, especially the program and hardware configuration. Uploading variable values will take longer, but it could be vitally important. All too often technicians write values to variables during startup of the machine but fail to provide a mechanism to allow the machine's owner to modify or even initialize those values. Worse, there may be no documentation, so you don't even know you need to be concerned about them.

 

[AutomationTechBrian]

Wow... I'm really glad I asked. I never thought about the volatile memory. Is there a special battery I need?

Thanks!!!!

 

[AutomationTechBrian]

....of course there is a special battery. I'm working google right now.