AB Remote I/O Scanner

hi all

I am still new for the AB remote I/O scanner and now I need to write a program to read remote I/O cards. So pls give me some advice in this area. Now I am reading the manual and I saw some sample program. I think I am using the Bidirectional Alternating Block Transfer.

Thanks in advance
gorillaz_sg

With the Allen-Bradley PLC products there are essentially three different PLC families. The PLC-5, SLC 500, and Logix5000.

I am guessing here that you are referring to the SLC 500 since you mentioned the Remote I/O scanner module.

There is a significant difference with how these different PLCs communicate with the Remote I/O. Can you please give us a little more info:

Speficially which PLC processor are you using. This would be something like a PLC-5/30 or an SLC-5/04.

Also, what is the catalog number of the scanner you are reading about? Is it a 1747-SN?

Next, what type of Remote I/O chassis or modules are to be configured? Are the I/O modules, digital (on/off) or are they analog (4-20mA)? This makes a difference as well. Digital I/O modules do not require the block transfer you asked about. Only analog and some other specialty modules require these instructions.

Lastly, what software are you using to perform this configuration? RSLogix 500? What version is the software?

Once we know these things we can offer much more usable help.

But in the meantime, if you are indeed looking to communicate from a PLC-5 or SLC 500 to analog I/O modules in a remote chassis then you are on the right course. You might even consider the: bidirectional alternating repeating block transfer method. But give us some more details and you'll get more detailed responses.

OG

Also if its an SLC then specifically which processor and what firmware revision is the processor ?

hi Operaghost

Ya u r rite i am using the SLC 500 and the processor is 1747 L551B/C 5/05 and RSLogix 500 version 7.

The catalog number of the scanner I am reading is 1747-SN.
And I need to configure AI card 4~20mA.

The attached file is the part that I don get it. The rest abit abit understand only.

The screen is captured from page D-25 example from 1747-SN manual.

Thanks in advance.

hi 504bloke


I think the reply just now got the enough information.


Thanks in advance.

gorillaz_sg said:

hi 504bloke


I think the reply just now got the enough information.


Thanks in advance.

Click to expand...

The reason i asked is because if the 5/05 processor has OS501 series C or above then you can use the BTR/BTW Instrucions, if its not then you have to do block transfers using the M files in ladder logic.

ya 504bloke I need to use the M file to do the block transfers. Pls help me out thanks

Read This first

Then read this for an NI4 example using ladder logic or this example for an NI8 module

Personally i would just upgrade the firmware in the 5/05 and use the BTR/BTW commands.

Thanks alot 504bloke I ll read it through. by the way where can I get the BTR/BTW commands sample programs?

Thanks again.

Heres an example of BTR/W with an NT8 which is pretty much the same as an NI8.

You may also want to take a look here.

First thing you need to do is upgrade the firmware revision of your processor to allow for use of the BTR and BTW instructions. This will make the Block Transfer procedure MUCH easier.

I would not recommend proceeding without the upgrade. Without the BTR and BTW, this is a procedure that requires a strong knowledge of the controller.

If memory serves me correctly, I think this upgrade may be free. Contact your supplier and they can let you know for certain. If it isn't free, it was pretty inexpensive, and one purchased update could be applied to all of your 5/05 processors.

OG

hi thanks to all friends
I think I understand abit more but I have another question which is "what is the logical rack? " As I understand I think it's just a mapping of the Remote I/O card to the scanner. But I don know how to map it? I saw ppl using Rack 0 Group 0 slot 0 for 000. Rack 0 Group 1 slot 0 for 010. But I don get it. Is it depend on the physically rack or ...?

Thanks again.
Actually I wanna update my firmware and I can use the BTR/BTW instructions but I think I have no choice because the first person who write this program write in this way I have to follow as my boss wish.

You haven't given any details on your remote I/O. But generally speaking you have to configure your scanner to match the ASB in the remote rack.

I don't have an ASB manual on hand, but there are three dip switch banks, that are used to set baud rate, type of addressing (1/2 slot, 1 slot, two slot), logical address and length etc...
I recommend you down load the ASB manual and ensure your switches are set correctly. If you have any problems, post back.


RIO has been around for a long time, when it started out, 8 bit processing was the standard.
So.... each logical rack is only 8 slots, if you have a physical chassis with 10 slots, it will have two logical racks, one logical rack for the first 8 slots, and then another for the remaining two slots. The preceeding was based on 1 slot addressing.

hi long time no see all friends

Past few days i ve been reading the manual and this part in the pic (config the G file) I not very sure. 1/2 rack means only using the group 0 to group 3 As far as I understand. But one group is one slot rite if 1 slot addressing?? If true, then I can use 4 AI or AO cards for rack 0 rite??

Thanks in advance
gorillaz_sg

I think you are on the right track but for the moment let's forget about slots.

With RIO the terms Rack and Group are important terms to know and know well.

First off,as you probably already know, the PLC memory is organized into bits and words. A bit being a single location for storing on/off data and a word is 16 bits grouped together to allow storage of a value.

A Remote I/O Group is one word of input data and one word of output data. Or sixteen input bits and sixteen output bits.

A Remote I/O Rack is (8) I/O Groups. Or 8 input words and 8 output words (128 input bits and 128 output bits).

Racks can be broken down into the following:

• 1/4 Rack = 2 I/O Groups
• 1/2 Rack = 4 I/O Groups
• 3/4 Rack = 6 I/O Groups
• Full Rack = 8 I/O Groups

A 1747-SN RIO Scanner Module is capable of 4 RIO racks which are numbered from Rack #0 to Rack #3. This means a total of 32 groups or 32 Input words and 32 Output words. The words are identified as 0-31.

Now as mentioned earlier, RIO is an older network that is based on an 8-bit numbering system. So what that means is that the Rack and Group numbering is in octal. The SLC 500 however understands decimal.

The rack # is combined with the group number to arrive at a word number in the SLC. So for example rack #0 group #0 combined would be 00 in octal which would mean word #0 (decimal) in the SLC. If you had a module in Rack #2 Group #4 then that would be 24 in octal which would be word #20 (decimal). So the very last address would be Rack #3 Group #7 which would be word # 31.

So when you configure the Remote I/O adapter (by dip switches) you must specify for that adapter how many groups it will use.

When you configure the Remote I/O Scanner Module (using the G File Config in software) you must specify how big each rack is and where it starts. Typically your first chassis would start at Rack # 0 and Group #0. But your first chassis could start at any rack # and any group #.

OG