Help with BTR and BTW instructions.

[hboyer90 3]

Hey guys, another beginner question here. Can somebody please explain to me what the BTR and the BTW instructions do/ how to use them in RSLogix5. I am a pretty novice programmer. I know that they have something to do with the analog, encoders and thermocouple modules on our machines, but I'm not sure how to set them up in a program. Can somebody please explain it in an easily understandable way? Also, I am currently working on converting a program (re-writing actually) from RSLogix5 to RSLogix5000 and I see that there is no BTR or BTW but it uses a message instruction or something? Any help understanding this would be greatly, greatly appreciated. It's been a couple years since I took my PLC classes. Thank you so much.

[Bering C Sparky 7]

Hello, I am a novice also and woking on a similar problem messaging between Compact and Micrologix. Anyway from what I understand about the PLC5 system we have is that the specialty modules, Analog, HSC, etc, are not directly addressed in the programing and you have to use read and write Block Transfers to and from these types of modules. Others will be able to explain in more detail. As far as using the messaging instruction here are a couple of links to other threads that talk about messaging, these are more specific to Comapactlogix to the SLC or Micrologix platform, but you can get links to lots of Rockwell literature from these threads that will help point you in the right direction. http://www.plctalk.net/qanda/showthread.php?t=58012 http://www.plctalk.net/qanda/showthread.php?t=82101 http://www.plctalk.net/qanda/showthread.php?t=73533 http://www.plctalk.net/qanda/showthread.php?t=77166 Sorry I could not be of more help, but I will watch your post to see if others give you any info that will help me along also. Have a good one. BCS

[Bering C Sparky 7]

Also as an afterthought, you say that you are rewritting your program in 5000. If you are going to be changing out the entire rack from PLC5 to Control or CompactLogix then you may not need to use any of these instructions as you will be able to write/read directly to/from the analog, hsc, thermocouple, etc modules that you will put in your new system. However if you are going to leave the PLC5 and use it as Remote I/O or something similar, then you may still need to utilize the MSG instruction to communicate with these modules. (I am not even sure if this second option is even possible with the PLC5 but I have heard alot in the forums about doing this with SLC) Again I am only understanding bits and pieces of this myself so, I to look forward to hearing a more indepth explanation. BCS Edited 27 Mar 2015 by Bering C Sparky

[Mickey 71]

See link... http://www.plctalk.net/qanda/showpost.php?p=16077&postcount=3

[hboyer90 3]

I am completely changing from plc-5 to new CompactLogix modules, not using remote i/o. So let's say that I have a Thermocouple module in slot 10 of my CompactLogix rack, and I had a thermocouple hooked up to input 1 and I wanted to use a greater than instruction on that thermocouple input I would address it as Local:10:I.? (as long as the module is configured correctly) and I wouldn't need a BTR/BTW or message instruction? In other words, the BTR and BTW and message are just for getting or sending data to modules that are connected via remote i/o or Ethernet or something? And since my CompactLogix has the module right in the rack that I don't need to use the instructions at all? I just address it like it was a regular input? Let me know if that is correct. Thanks.

[Bering C Sparky 7]

Generally speaking, yes it will be somthing like that. You should not need Read/Write transfer blocks when switching completely to compact logix. (I dont know your entire layout so you need to consider if there are other factors involved) But it is a bit more complicated than that. First you need to know what Compactlogix you are using. Then look at each module in the PLC5 rack and see if they make a similar module for your compact logix. If they dont then this may throw off your module sequence and logic behind the way you are planning this. Also is the Compactlogix you are planning to use capable of having 10 expansion cards attached to it? Do you need even more than 10? Best to plan what hardware you are going to use to replace each piece of the old PLC5 rack and go from there. For each expansion module you pick you can download a data sheet that will show you how it needs to be addressed. Until you know exactly what you are going to use, it is hard to say how you will address it. You dont want to rewrite and entire program and then figure out "hey this is not going to work". Also if your PLC5 is anything like ours you may want to look at any HMIs that are on the system also. All of ours for the PLC5 system are either DH+ or RIO. The comunication for the RIO HMI also uses Read/Write Transfer Blocks. Since you will be going to an entirely different platform you will likely need to upgrade your HMIs also. BCS Edited 27 Mar 2015 by Bering C Sparky

[Bering C Sparky 7]

You can download for free from the Rockwell Automation Site a program called "Integrated Architecture Builder" This software will let you put your system together online virtually. It will also allow you to get the manuals and lots of info for each piece simply by clicking on that pieces icon. This software is a little hard to start using at first until you figure it out, but just give your local A.B. Rep a call and they should be able to walk you through it and get you started. BCS Edited 27 Mar 2015 by Bering C Sparky

[hboyer90 3]

We already have that all sorted out, I have everything assembled already, just working on writing the program in the new software. But thanks anyways. My AB rep helped me find all the modules we needed for the conversion as well as power consumption, how many power supplies we need, the right cables, RIO adapter modules, etc. We have quite a bit more than 10, we have 28 haha, and we're pretty full at that, but we have the ability to add up to 2 more modules if need be, then we will be at our limits.

[Bering C Sparky 7]

And there are the magic words that may mean you will need to use some sort of message instruction. Hopefully someone a lot smarter than I am will step in here and help you out. Good luck BCS Edited 27 Mar 2015 by Bering C Sparky

[hboyer90 3]

Ah, I'm dumb. I forgot, yes, we actually will have a few thermocouple modules and output modules that control the furnace that will be remote.

[Guest]

a few potential "gotchas" to consider ... if you're keeping some of the PLC-5 hardware, be aware that the digital modules are marked for OCTAL addressing ... but ... the ControlLogix data tables are marked for DECIMAL addressing ... so ... suppose that your technicians are looking at an LED on an output module and suppose that the LED is number 13 ... the bit located in the data table won't be numbered 13 ... it will be numbered 11 instead ... this can throw off your technicians who might be used to the older addressing and it can render your documentation and your wire number labels incorrect as well ... DISCLAIMER: this is all based on what COULD happen ... you haven't provided enough detail for us to really nail down specifics ... moving right along ... some of the channels on your PLC analog modules might have been numbered ONE through EIGHT (for example) ... but ... the ControlLogix data tables (arrays) might be numbered ZERO through SEVEN ... once again, this might possibly skew your documentation and your wire number labels and confuse your technicians ... it's quite common for a technician to spend an entire shift trying to track down a problem with Channel 3 (for example) only to realize that he SHOULD have been troubleshooting Channel 2 instead ... one more about your analog I/O modules ... the RSLogix5 software had the capability for automatically setting up the "configuration data" to be used by your Block Transfer Write instructions the RSLogix5000 software can't do that operation ... so ... it's a good idea to carefully copy down the specific data table values (example: 0, 0, 1280, 0, 16533, 0, 16533, etc.) from your old PLC-5 program file ... then carefully type those values in to the data table locations that will be used by your ControlLogix processor's Message instructions for the purpose of "configuring" your analog modules ... good luck with your project ...

[hboyer90 3]

So I talked with my Allen Bradley rep a little bit about it and he said that I wouldn't have to use any btr/btw/message instructions because the thermo modules that I was using BTR and BTW for are now going to be replaced with modulus that communicate via Ethernet, so they will be addressed just like they were local modules. Does that sound right/make sense/ could someone elaborate on what he's saying? Thanks

[Guest]

yes, it makes sense ... I wrote my answer earlier post based on the idea that you would be keeping SOME of your existing PLC-5 hardware (modules) ... replacing the older system completely will make the transition easier ... a lot of folks keep their older hardware - and just replace the controller ... you asked about BTR and BTW operations - so I tried to answer those questions ... no harm done ... maybe the information will be useful to someone else someday ... TIP: if you have any other questions, it would be helpful if you could supply us with specific catalog numbers for your hardware ... you'll get much more detailed answers that way ... good luck with your project ... Edited 1 Apr 2015 by Ron Beaufort