Thread Starter

Gary Green

I am looking for information on how to download a program from a AB SLC 503 PLC. The company which did the press retrofit for me is defunct and I didn't get a copy of the program. Is there any way to download it from the PLC?? Any and all help would be appreciated
First, you will need a copy of Rockwell Software's RSLogix500, and a serial cable.
You can perform an upload of the program from the PLC's memory to your computer but unfortunately, you will not get the rung descriptions or comments with it. You would need the original program for that.

More help can be obtained at

David Lawton Mars

I take it you want to upload the program from the processor rather than download it?
Yes you can upload the contents of the processor, the only drawback being that you won't get any comments in the program since they aren't stored on the processor. You have a few options to do it.
First of all you'll need a copy of RSLogix500 (Windows) & RSLinx or APS (DOS)
To connect to the processor you can either use DH485 or RS232. You need a PIC box part no AB1747PIC if you use DH485 or alternatively you need an RS232 programming lead part no. 1747-CP3 to go on-line using RS232.
If you use RSLogix you need to configure the appropriate driver in RSLinx and then you can select upload and suck the contents out of the processor. I'm not too familiar with APS but I'm sure there's an equivalent way of doing it.
If you're struggling please e-mail me directly or phone Rockwell tech support.
[email protected]
As stated previously, you need RS-Logix and they sell an adapter cable to go from the PC serial to the SLC. Neither are cheap. Also you need a computer (laptops are great) that can go out on the floor and attach to the PLC to download it.

Unfortunately PLCs don't keep the documentation inside the machine. You really should make another attempt to find the people how did the upgrade for you. It doesn't sound like you know PLC ladder logic, so there is another learning curve there too.

One place to look for help is your Rockwell/AB distributor. They often will be able to help you. I know the places like McNaughton & McKay and others have support staff that could bail you out for a reasonable fee (if you buy enough stuff it might even be for free). AB will also come out and help you for a slightly higher fee.

Another is to find a freelance controls engineer with the tools to download the code. He can take whatever documentation you have and at least get the I/O identified in the program and give you a printed copy along with a floppy that contains the program.

As a note, you may be on borrowed time if you can't get the original code from the original controls house. If anything happens to the PLC and the memory dies, you will need to start from scratch, unless you have a paper copy of the code in which case it will need to be entered back in by hand.

Tom Bray

> First, you will need a copy of Rockwell Software's RSLogix500, and a serial cable.

> You can perform an upload of the program from the PLC's memory to your computer but unfortunately, you will not get the rung descriptions or comments with it. You would need the original program for that. ...

Ralphsnyder, Grayg

With a copy of Allen-Bradley's RSLogix-500 (or any other version of it) you can upload a copy of the program from the SLC memory to your PC harddrive. You will have to add appropriate comments and descriptions as the SLC does not store this information in its memory.

I do not know if any other company makes this type of software.

Grayg Ralphsnyder

You will need RSLogix500 (it comes with RSLinx Lite) and a cable for DH-485 communications. It will cost you about $1500.00 to buy it or you could hire someone to do it for you. If you don't have a copy of the program now you are out of luck for symbols/descriptions on the I/O points and internal elements, as that info is not stored in the SLC.

Sid Roberts

[email protected]

J.J. Overyton

Go to and look for the pubs for the slc503 instruction, you will need the reader because they are in pdf format. It is also downloaded from the site.
Where are you located? Maybe someone on the list could help you out for a small fee or free depending on how they're feeling.
Darin Jett

Daniel Boudreault

Hello list,

I got an e-mail from Gary Green about his inability to download the program from his plc. His PLC has the Access Denied S:1/14 bit set. So, without the original program on disk, he can't make changes to his PLC program.

He'd like to know how to get around the protection.
This post has been replied to extensively, and most of the posts have been correct: to upload a program from an Allen-Bradley SLC-500 controller you need a serial cable or network interface (depending on SLC model) and RSLogix 500 software.

All A-B distributors, all A-B local offices, and most control systems integrators have this software. Gary's e-mail address indicates he's in
Ohio, home state to Allen-Bradley Control and Information Group, so there should be no shortage of A-B presence. Three minutes with the phone book under "Electrical - Wholesalers" should suffice.

One very important detail stuck out of the original post: "the company which did the press retrofit for me is defunct and I didn't get a copy of the program". If this is running a metal forming press, it is very likely that the programmer employed the "OEM LOCK" in the SLC-500, which means that a person who does not have the exact program in the SLC cannot upload or go online with the SLC. This protects OEMs with proprietary logic and protects especially metalworking OEMs from liability coming from
somebody else modifying their logic.

I have seen the OEM lock employed by integrators to assure they are paid; I have heard the "they went out of business, I never got a copy, the guy is on vacation in Brazil" a dozen times from guys who never paid their programmer. That doesn't mean it's not true in Gary's case (one of my
stories really was in Brazil), but it does mean that if the OEM lock is set, then Gary is either up the creek or he's going to have to try to get
in touch with the receivers of his bankrupt vendor.

It's trivially easy to safeguard floppy disks from loss and damage. Keep good track of those *.RSS files, guys. It can cost a lot if you don't.

Ken Roach
A-B Seattle
[email protected]
I have heard that Rockwell Software has a master password that works with all PLCs that are OEM locked. However, they reportedly will not give out the password, nor will they use it to retrieve a program froma PLC unless you pay for a GTS guy to come out.
Hi List


Do you go on line and get the message "This program has been PROTECTED from user access" or are you being asked for a password? AB do have a password to override password protection but I am not sure on OEM protection.

Allan Dow
Embedded Systems & Solutions
Hi all,

Actually there is no master password per se', for the SLC500's. But there is a way in and a way to delete the oem locks and access denied bits.
The Software package that is sold to the public is what determines if you have access or not. It looks at bits that are set or not set in the system, looks to see if you have a file that has a matching CRC (checksum).

I have worked this out by using a dumb terminal and sending the proper commands and addressing to the SLC systems. I write zeros (0) to the proper
addresses and in turn over write the locks. Then I am able to go online with RSLogix and extract the program.

Piece of cake. Not.

If a person would like assistance please E-mail explaining your predicament. I may or may not help. Companies have reasons for locking your

Best Regards,

Sorry to disappoint but there is a master password "per se". Either that or I just happen to type in the right sequence of characters and
bypass the password everytime. Ah a rose by any other name...

Allan Dow
Embedded Systems & Solutions

Clifford Jones

Search the net for "handheld HMI"
There is a Palm Pilot application
which allows clearing the protection
bit. This will then allow you to
upload the SLC503 program to your
computer using RS Logix software.

Good luck

Cliff Jones
well, there is RSLogix500 or DOS based good old "APS" s/w
the former software comes with a software lock(needs to buy one)
APS files can be copied, I can give u for FREE
just email me at [email protected] for any AB's software
the list includes APS, IPDS, Panel view 550, 900, 1200 etc etc
well the real question,
load free APS software (if DOS based), select driver as Full Duplex, make sure it is connected to SLC 5/03 channel 0 port(9 pin)
select baud rate as 1200(default, may need to be changed), & press who active
if every thing is allright, u whould see SLC's as a node other than your PC
point to the device (SLC) & press online, once u are online, upload/or download the SLC program,
as simple as that??

vivek samyal

I understand u have bit S:1/14 set on the SLC 5/03, thereby without extact replica of the program in the PC hard disk, the PLC program cannot be accessed
I have a weird idea, wonder if this would work??
why not connect an HMI (like DOS based AB's Control View), the reason for DOS based, there's no software lock, & i can give u software for FREE, my email is [email protected]
Load Controlview HMI on a DOS based PC, use any RS232 serial cable, can be easily constructed(if u have a AB's cable, that's good)
connect the PC serial com port to the SLC 5/03 serial port (channel 0, 9 pin connector), configure Control view communications, as serial device, try different combinations of baudrates, CRC or BCC, & node address(most probably 1, of the SLC). Establish communication between Control view & SLC
Then create a digital tag, address it to S:1/14 or any bit u wanna change. set that tag to 0 or 1, as the case may be.
I think this should theoretically work
if the digital tag can be altered, then the program can be uploaded with APS or RSLogix500
waiting for comments on this
vivek samyal

Barry Mueller

I read your answer to a question posted on getting past a password, i need help immediately. I contacted A-B GTS, but they are really backed up... We are an OEM, and I have a 5/04 processor with a password that was left by a former employee, and we have a change in progress and need to change the program. Can you provide some assistance on getting it off or around it to upload the use file?
Barry Mueller
509 969 1630
I am in need of assistance to "crack" an SLC503 password. The OEM is bankrupt and the customer is without a backup program. The machine runs fine ...for now.

As for GTS we really dont want their folks mucking with our clientbase if we can help it.

[email protected]