Modicon to AB

[bwest]

I have been given the tedious task of converting an old 484 Modicon program to a new AB SLC5/03, and have never touch a Modicon before. Is there any programs for converting the programs? or do I just do it line by line. And are they any pit falls I should watch out for?

Regards

 

[BradJ]

Sorry, I think you're looking at line-by-line.

I can't recall if the 484 had the network-vs-rung structure, but if it does, keep in mind that the 7x11 network solves vertically first (solves the first column, then the second column, etc.), regardless of rung structure. This can really kick you in the backside if you are not aware of it.

-Brad

 

[Mike6158]

Might be able to save some documentation time by exporting the docs to a CSV file (if possible) and then importing them back into RSLogix after you make it match A-B's clutter.

 

[Fchild]

I have the same issue as stated above. I am converting Modicon 484s to SLC 500. I am going through the documented program (unable to online with the Modicon) line by line. I have some contacts in the program with a 2100 address. I am unable to find where these are coming from. There is no I/O associated with the address, no timers or coils. Are they some kind of internal status register? Any help would be appreciated.

 

[mcgowan]

fchild...with out knowing the aplication i can only guess!
However i would say you 2100 address are coming from an HMI...With modicon they use an output adress for an input from an HMI...(Sounds confusing dont it!!) This takes a while to get your head around...But if you have the instructions and no in/out that seems relivant then that is what i would put my money on..

 

[scubabeme]

And address in the range to which you referred could be a value being "poked" by an HMI, but it could easily just be a "holding" register, i.e., a memory location that the PLC uses for temporary storage of values while it processes the rest of the logic.

Be aware that some instructions may actually use more registers than is shown on the function block. Many math functions will use a set of contiguous (i.e.: 42100, and 42101) registers, but that's more of a concern when developing for that PLC, UNLESS--the implied register is used by logic elsewhere, which would contribute to the mystery of "where's this number coming from?" In short, you would benefit from a manual describing each function block and it's register usage. Unfortunately, I have no experience with modicons older than the 984 series so I can't help with specifics--though yours MAY be the same as 984s and later.

To get a book, goto

http://www.modicon.com,

click on search (very small in the upper left area of page) and search for 840USE10100. The first result returned should be "Modicon Ladder Logic Block Library". You can download a PDF of the book from there.

 

[youngrj]

The 002100 address in Modicon is what they call an internal coil. Some internal coils are then mapped to physical output through the traffic cop. If an internal coil is not being used as an output, think of it like an AB B3 file bit. If there is no actual coil in the logic then it is almost certainly being set by an HMI.

As one of the previous posters noted, one of the big differences between AB and Modicon is scanning top to bottom vs left to right. It can get you if you're not careful. Another big difference is the (L) coils. In Modicon these are not really latching coils like they are in AB. Modicon really doesn't have the equivilent to (L) and (U). In Modicon the (L) coil tells the processor to save the state of the bit on power down and turn it back on at power up.