RSLogix 5000 and RIO Fundamentals.

antsrealm

Member
Join Date
Dec 2010
Location
Brisbane
Posts
207
Hi,

I'm new to the RIO component of rslogix 5000 and was looking for some help understanding how it works and where the messaging comes into it if at all.

I have a project on at the moment that consists of the following :-

Control logix rack:-

1756-L61
1756-ENBT
1756-DHRIO
1756-DHRIO

PLC5 Remote IO rack attached to one of the 1756-DHRIO cards above:-

it has 15 cards in it and uses a 1771-ASB card to link with the 1756-DHRIO.

Of the 15 IO cards they are mainly digital in and out and a couple of analog cards in and out.

Now my objective is to upgrade this control panel including completely replacing the panel and full re-wire. The remote rack will be replaced with a control logix remote rack and cards. Now the guys I am doing this project for thought they could purchase a second 1756-DHRIO card and link two of them together and use the new control logix rack in the same way as the PLC5 rack. As it turns out from my research these cards are both scanners and would not work together. So... I am thinking the best thing to do is put a 1756-enbt in the remote rack and add it as ethernet remote IO. Can someone confirm if this is the best way to go here ??

Now the next part of my dilemma is identifying everything in the code that is related to the old PLC 5 remote IO addressing and changing it to suit the ethernet remote rack that is now control logix hardware.

As I am not to familiar with remote IO and the messaging components can someone steer me in the right direction to understand how the PLC5 remote rack is being addressed in the control logix processor at the moment.

It seems that the one rack has been split into two racks in the rslogix 5000 tree, the first one containing 8 cards and the second containing 7 cards. Now I can see default tags associated with this and they are aliased to other tags that are used in the program. That makes sense for the digital IO but it's the analog IO that i'm not sure about. How can I find the tags for an analog card in say the 7th slot of the second half of the remote rack?

I think they are using message instructions (Block transfer read and write) but I'm not 100% sure. Can someone maybe give me some advice here to steer me in the right direction.

Thanks,
Tony.
 
You are correct that there is no "Adapter Mode" for the 1756-DHRIO.

There's an Adapter Mode for the 1756-RIO module, but it needs to have a controller in the chassis, so that's really for emulating the old PLC-5 Adapter Mode connectivity.

The appropriate method for connecting the remote chassis is a 1756-ENBT in that remote chassis. It can bridge both discrete and analog I/O module connections.

Now back to the PLC-5 Remote I/O architecture.

The old RIO architecture's memory organization is based on 8-word blocks, which are called 'logical racks'. As you've seen in the rack objects in the 1756-DHRIO's scanlist, there can be multiple logical racks of I/O memory in a single physical chassis.

Analog modules require Block Transfer instructions. In the PLC-5, these instructions were literally named "BTR" and "BTW", but in the ControlLogix they are MSG instructions with the BTR or BTW function code.

Look for MSG instructions in the program that are aimed at the Rack numbers of the logical racks. If there is just one chassis, the racks are probably Rack 00 and Rack 01.

The "rack/group/slot" addressing method can be tricky to explain, so let's figure out exactly which modules are in exactly which slots, and see if we can line those up with the associated MSG instructions.
 
Thank you Ken for the solid info. The results of my on going research today indicates that as you suggested there is 2 logical racks making up the one physical chassis. Now I believe it is in single slot addressing and I found the related MSG instructions that are doing the BTW for the cards config. I have deciphered the old manuals and worked out the config for the first analog card. Big progress for me :)

I have dropped a 1756-ENBT I had here into the replacement rack and added it to a spare L32E that I had lying around and that was a very simple process.

Now the scaling in the BTW for the channels on the old PLC5 analog card were 0 - 4095. In order to minimize the amount of software changes I have to do in this upgrade should I simply set the scaling of the new control logix card to match these values ?

Another thing... these guys have also already purchased the analog cards without doing a lot of research. They got a 1756-IF6I and it doesn't have a selection for 4-20ma but does have 0-20ma. Now from the BTW config I worked out the existing card is either 1-5v or 4-20ma (don't have physical access at the moment to check jumpers). I suspect it is 4-20mA. Can I use these cards that lack the 4-20mA option or should I order something else?

I think for the most part I am now on track. Thanks for the guidance certainly helps to put my mind at ease that I'm heading in the correct direction.
 

Similar Topics

Hello all, I have a question in regards to RSlogix 5000. I am having issues with the program force closing when I try to make online edits. We...
Replies
0
Views
95
Greetings ... someone sent me a request for some student handsouts that I developed ... turns out that I had this hosted on my business website...
Replies
0
Views
109
Thank you for any and all responses/help. I have an RSLogix 5000 v20 and a Cognex In-Sight v5.9 spreadsheet (8502P). I can not figure out how to...
Replies
0
Views
101
Hi All, I've been pulling my hair out trying to fix this for a few days and need some advice. I have V19.01, v20.05, V21, V24, V30, V31, V32...
Replies
5
Views
348
Hello Friends I have a installation with v16, v17, v18, v19, v20. When I tried to open a v20 file, the enable source protection was not enabled...
Replies
1
Views
214
Back
Top Bottom