SLC 500 communications error after download

stallone

Member
Join Date
Oct 2010
Location
south africa
Posts
172
Good day ,
i am new to SLC 500, i have a plc SLC 5/03 that had the battery go dead and lost the program.
I replaced battery and reloaded program using the rs232 df1 driver.
I did a successful auto configure and then i could browse to the PLC.
I opened the program in rslogix 500 ver 7.1.
I went to comms, system comms and downloaded the program, it completed successfully with no errors but when i try go online it says diagnositcs status failed 0x4 and also no response from processor at that path.

After i downloaded the program it pops up to say apply new configuration or dont apply and you could lose comms, i tried both options and have the same issue.

There is no fault on plc or anything but i just cant go online after downloading the program again, its like it loses comms after its downloaded.

Can you please see if i am doing anything wrong.

Using windows xp sp2 32 bit.
SLC 5/03
Rslogix 500 ver 7.10
Rslinx 2.55.00 classic gateway
using a rs232 serial usb convertor, non rockwell but its worked before.
 
Your channel 0 port (the DB9 port you are connected with to download the program) is configured in the file you attached as a DH485 port. When the processor loses its program the port defaults to DF1 full duplex which is why you can connect to it with RSLinx. Once you reload the program it goes back to DH485. If there is something connected to the both ports when the PLC is running it's application then you need to get an DH485-UIC adapter so you can talk to the PLC after the program is loaded. If there isn't anything connected to the channel 0 port then simply change the configuration in the program by setting the channel 0 port to DF1 full duplex (19200 baud) and it will continue to work after you download. If the channel 0 port is occupied but the channel 1 port isn't (the RJ45 port) then you could move the comms over to the channel 1 port and change channel 0 to DF1. At that point it might be easier to get the DH485-UIC adapter but that's your call. Having said that I don't see any messaging in the program so I'm guessing the channel 0 port is available. Again, if that's true just change it's configuration in the program to DF1 full duplex.
 
Thank you @Firejo forbthe helpful answer.

So all will be ok probably and run as it did.

How do I change the configuration in the program or where I suppose.
So if I need to make changes and edit I will have to have the uic?
 
Configuring the channels (communications ports) is done using the "Channel Configuration" branch under "Controller" in the Project configuration section of RSLogix 500 (left side of the screen). The DB9 connection is "Channel 0" and is the only one that can be configured for DF1 full duplex. If there is nothing attached to the channel 0 port then there isn't any reason you can't change the configuration from DH485 to DF1. If there is something attached it gets more complicated. You will only need the DH485-UIC if you are not able to change channel 0 to DF1.
If you can change channel 0 to DF1 (I.E. there isn't anything attached to it) then you should be OK assuming you are comfortable making the change. If however there is something attached to channel 0 and/or you are not comfortable making the change yourself, you may want to solicit some help from your local AB distributor or a systems integrator.
 
There is a serial cable connected to the port but i think its just a programming cable, i will only know when i get to site tomorrow.
But if i just change battery and load original program, is there a way to just leave the configuration as it is in the program, becuase this worked for 20 years
and i dont want to change it.
 
Yes but you won't be able to go online with the processor after the program loads and you may have to manual put the Run/Program switch into Run mode when you're done.
 
What is the best way to do it then.
I have the comms to browse and download program but after I say dont apply the change in comms I lose connection. Is this because the baud rates are different to each other. After I lose the comms I just cant seem to get it back again unless I reset plc and take battery out
 
What is the best way to do it then.
I have the comms to browse and download program but after I say dont apply the change in comms I lose connection. Is this because the baud rates are different to each other. After I lose the comms I just cant seem to get it back again unless I reset plc and take battery out

If you answer yes to applying the channel configuration changes, you will be kicked off line, but the download will be completed. The (small) problem is that the PLC will most likely stay in program mode. To get it running, flip the keyswitch to PROGRAM, then back to the RUN position.

That will get the PLC running with all the logic, data, and channel settings from the file you downloaded. As long as that information is correct, it should run the same way it did when that file was created.
 
Ok thank you but what if I want to stay connected and go online. How do I do that without losing the comms

5/03 ?

Buy this:
https://www.plccable.com/allen-brad...Hg1uf_k9XcQSxql_iohi0lXZcnNJxooRoCHb0QAvD_BwE

Then you can make use of the DH-485 port with the RJ45 jack and connect the other device to the RS232 port, perform online monitoring, upload, download, etc. I don't think you can stay online with DH485 protocol on the RS232 port (channel 0) unless you hold your tongue just right and are lucky enough to set up the old driver and get them to work.
 
Ever decreasing circles...but you'll get there!...

stallone said:
...what if I want to stay connected and go online...

See post #2...

Firejo said:
...you need to get an DH485-UIC adapter so you can talk to the PLC after the program is loaded...

Then post #10...

OkiePC said:

That link is "broken", it appears?...

Try here for same...

https://www.plccable.com/allen-bradley-1747-uic-usb-to-dh485/

Regards,
George
 
Last edited:
Thank you for the replies.

It turns out there is a scada pc connected to the rs232 port on the plc.
Surely this will lose comms now if I have these issues with my laptop.
 
Another couple of circles to go yet...

stallone said:
...It turns out there is a scada pc connected to the rs232 port on the plc.
Surely this will lose comms now if I have these issues with my laptop.

First...

The fact that you cannot go online after the download is because you downloaded using the DF1 protocol on Channel 0, which the processor had defaulted to, but then after the download Channel 0 is now set to the DH-485 protocol.

This is because, and as explained, in the offline copy of the program you are downloading, the RS-232 Channel 0 is configured for the DH-485 protocol.

When you download the program using DF1 protocol, you are prompted near the end to accept the fact that the download is about to change the RS-232 Channel 0 configuration from DF1 to DH-485 protocol. The download is now completed, but Channel 0 is now set for DH-485. So you can no longer browse, download/upload or go online with the processor through Channel 0 and the DF1 driver in RSLinx Classic.

Secondly...

Just because the port is now configured for DH-485 protocol, and "you" can no longer connect to it, does not mean the SCADA PC cannot connect to it. If the program you are downloading is the correct original program, and in this program Channel 0 is configured for DH-485 protocol, and the SCADA PC has always been connected to Channel 0, then the SCADA PC has always used the DH-485 protocol to communicate with the processor. It should be able to resume communications the same as before the processor's battery failed and cleared the program from memory.

Also to reiterate...

If the top Channel 1 native DH-485 protocol port (fixed for DH-485 protocol) is not in use, then purchasing an adapter, like the model we linked, would probably be the best option to use this top port and the DH-485 protocol, going forward. I always recommend anyone working with SLC processors to carry at least one such adapter, as the bottom RS-232 Channel 0 on any of these controllers could potentially be configured for DH-485. But when it's set for DH-485 on an SLC 5/03, now both ports are using DH-485 and you will need an adapter for sure.

SLC503_Front_View.jpg


Regards,
George
 
Thank you for the replies.

It turns out there is a scada pc connected to the rs232 port on the plc.
Surely this will lose comms now if I have these issues with my laptop.

What I would do is look at that PC first to determine the comms settings it needs to communicate serially with the PLC. You might find out that the settings are fine and you just need to apply the changes to the PLC and reconnect it, or you may learn that something has been changed. In any case that is important information for you to have.

Where did you get the program you intend to download? Are you sure that program has the correct channel settings?

Unless I uploaded the program myself and saved it very recently, I never 100% trust it to be an exact match. Even if I saved it myself an hour ago, how many setpoint changes have been made by an HMI or SCADA on a network during that hour?
 

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