Micrologix 1500 LRP Indirect Addressing

I can't believe I would need assistance on this issue, didn't think this would be a problem.

Anyways, I just bought a Micrologix 1500 LRP plc in order to do some recipe control with the aid of a barcode reader. I did all my testing on the LSP version so I know the program would work but guess what, my program is telling me that the LRP doesn't support element indirect addressing... Seriously? Why would the LSP and LRP have a difference like that, the only difference I thought there was is the additional com port the LRP has, not to mention the LRP I believe is newer.

My question is am I doing something wrong? I'm asking because I feel that this should work but it doesn't. If for some reason this actually isn't supported, can anybody think of a different way of doing this?

Attached is my program, which I hope people can read through. This is what happens, a barcode reads a part# and then I have some code to determine if it's a barcode that is new or that has been used before. If it's something old then the parameters that were made for that part# are called up and are sent to a different plc. If it's new then the user will have to give it some numbers then they have the option to delete or save that recipe only once. They can save a recipe at any time only if input I:0/0 (key switch) is on, this is another layer of security as I don't want anyone being to save without good reason.

Hopefully someone can spot a mistake I made or has a suggestion to make this work. Logix500 apparently doesn't like the indirect addressing to string (compares and copies). Again, this works for a Micrologix 1500 LSP and can't for the LRP. Also, can't use the LSP due to memory constraints in case somebody asks that.

EDIT: Wow, completely forgot that the previous test I had was in a slc 5/03, not a Micrologix 1500. So that's why I can't do the indirect element addressing. Is there any other way to do this within a Micrologix 1500?

My RSLogix 500 copy (8.30.00) lets me indirect address file N7 for both 1764-LRP Series B and C...When switching the RSLogix 500 application CPU type from LSP to LRS the Data Tables will be re-sized unless choosing "Clear I/O"...Probably the Data Tables re-sizing causes your indirect addressing to be "undefined" if you are sure you are entering the proper indirect addressing "grammar"...

dmargineau - he's talking about strings - 'S' data types. I tried and the behavior is different between the two models rearding indirection on string data types.

It does support indirect addressing just not with the file type you are trying to use it with. See picture important note.

dmargineau, Bernie is right I'm reffering to indirect addressing for strings specifically. As Mickey has pointed out, I can't do indirect addressing which is not good.

For those of you that have looked at my program, is there another good way to compare a string to a database of strings? Currently the database is set at 50 strings... but that number will change to the max amount of recipes (256 if I recall correctly), so 256 string compares is just silly. Now, this PLC will be connected to 3 other SLC 5/03's, so I may try to do the compare within one of them IF it has the memory to hold all the strings. Can you send a string in a message (MSG)command? I can't check this right now or else I would look this up.

If anyone has some suggestions that would be great.

Upgrade your ML1500 to a ML1400. Ethernet and online editing. And "ST" type ok to use with indirect addressing.

Going to a 1400 would mean different add-on I/O, if he has any.

bernie_carlton said:

Going to a 1400 would mean different add-on I/O, if he has any.

Click to expand...

The program he posted did not show any, but you are right.

I have a grand total of 1 input on it currently, highly doubt anything more would be added to it. So that's not a concern.

After a brief look at the ML1400... looks like I should have went with that. Seeing as I need to communicate between 5/03's Ethernet won't help but it does support DH485 which I would expect it too. You can message up to 2 ST at a time so what I will end up doing for this case is just using a different PLC'S memory and doing the compares in there then sending the value back to the ML1500. If I ever have a project like this again I'll go with the 1400.

Thanks for the help.