SLC 5/01 plugged ethernet in

Hey guys,


I've been placed fresh on a site with minimal handover.
Another contractor was said to have plugged an ethernet cable into a SLC 5/01. I'm fully aware this is not the communication method the card uses but I need some help in determining the best course of action.


The PLC still runs fine and apparently has been for a couple of months but after bringing this to my attention, I've taken it onboard to get a suitable back up so that when something goes wrong we can have minimal downtime.
I was told the plc just turns off when a cable is plugged into (whether they mean the original Ethernet or DH-485 I am unsure).



Considering the cpu card still runs.. is it likely that the card is just damaged or could there be an issue with the chassis? I don't really have much downtime to do an investigation and they just want a solution.


I was thinking just buying a SLC 04 or 05 (I'm aware of the communication differences).. but should I buy a Chassis as well?


So the options are:

• Replace CPU card (with the potential the Chassisis damaged)
• Replace CPU card and change CPU slots (potential the Chassisis damaged)
• Replace Chassis and no CPU card
• Replace Chassis and CPU card

Hoping someone has a little more insight with this problem.




Cheers!

The communications port is isolated from the rest of the controller on purpose so that interference on the DH-485 network cannot affect the I/O system.

That means that when you smoke a network interface, it affects only that part of the controller. If the Inputs and Outputs and operation of the machine are otherwise working correctly, then only the CPU is damaged and the chassis, power supply, and I/O are otherwise undamaged.

The DH485 port has a live +24V pin, and if that is plugged into an Ethernet switch it destroys the Ethernet port. If your controller is shutting down when something is plugged in now, it's probably because the internal 24V power supply is self-protecting.

Interesting, Thanks for the help Ken.


I've been avoiding plugging in my 1747-UIC just in case the PLC was going to do damage to it or my PC for some reason... but there's a chance it might work?

If you have the logic, another option would be to get a newer PLC (compact logix and such) and put an AENT card into the CPU slot and use the old chassis as remote I/O. This plan is dependent on whether you are using the communication options on the PLC for other uses, or if the chassis has actually failed. I'm not familiar with the 5/01 myself, oldest I've worked with has been a 5/04, but have taken a failed 5/05 and ran this way while waiting for the time to perform an upgrade. Last I checked the cost of an AENT card is about the same as a SLC processor, but this does lay the groundwork for a future upgrade.

godcixelsyd said:

If you have the logic, another option would be to get a newer PLC (compact logix and such) and put an AENT card into the CPU slot and use the old chassis as remote I/O. This plan is dependent on whether you are using the communication options on the PLC for other uses, or if the chassis has actually failed. I'm not familiar with the 5/01 myself, oldest I've worked with has been a 5/04, but have taken a failed 5/05 and ran this way while waiting for the time to perform an upgrade. Last I checked the cost of an AENT card is about the same as a SLC processor, but this does lay the groundwork for a future upgrade.

Click to expand...

Thanks for that, Though given how much stuff I have to catch up on the upgrade wouldn't happen until 2020+.


I'll just go with getting a new card for now and when it comes time to upgrade the entire unit ill just wear the cost. We have a few machines onsite with 5/01's, so I could always use some good spares.

I've been avoiding plugging in my 1747-UIC just in case the PLC was going to do damage to it

Click to expand...

That's a great question.

The +24V DC pin on the DH485 port of the old SLC-500 controllers was built to power devices like the Hand-Held Terminal and the classic 1747-PIC.

But the 1747-UIC is powered from the USB side, and needs no power from the DH485 port.

The cable you use to connect a 1747-UIC to the SLC-500 is part number 1747-C13. A Rockwell Knowledgebase article (KB 823750, access level Everyone) reminds us that unlike the 1747-C10, -C11, and -C20 cables, the 1747-C13 omits the +24V and Earth Ground conductors.

So if you use a proper 1747-C13 cable, you can very likely connect to the DH485 port without causing a short circuit on that pin, which is very likely why the controller shuts down when plugged in.

No guarantees, but I like your odds.

Thanks again Ken.

A few further questions (my 500 series knowledge is pretty limited).

The chassis is a 1746-A10 (Series A) . Built in 1990.
If I buy a Series C chassis the Series A CPU card should have no issues right?

From my understanding the Series A has a 1MW resistor between chassis ground and logic ground.

Also if I bought a SLC 5/04 Series C card, could you foresee there being any issues it in the original Series A chassis?

The principal differences between Chassis series were the way the ground was connected; you'll see a cluster of MOVs under the Slot 0 location on some old Series A's that you had to be careful not to crush or interfere with the CPU.

The 1746/1747 hardware is about as universally backward compatible as anything in the industry. Any module will fit in any chassis with any power supply of any series letter.

There may be exceptions, but none are coming to mind at this time.

Gotcha, Thanks Ken