Logix Distributed I/O Suggestions

free_agent_7 · Jan 24, 2017

Hello All.

I want to add distributed I/O to an existing AB PLC installation that probably should be upgraded. A visit to Rockwell/AB site usually creates more questions than answers, if you know what I mean.

The PLC is 1756-L62 Logix v15 (I'd like to avoid having to ControlFlash it up for the time being, but if that's what I have to do then OK). Backplane has 1756-ENTB/A for comms.

I am looking at 1734-AENT with Point I/O or 1794-AENT Flex I/O to add 8 remote analog inputs, but it seems (according to the pdf from AB) that I won't be able to use the 1734-AENT with the current controller?

At the end of the day I just want to add 8 remote analog inputs via Ethernet/IP. I don't care if it's AB or some other brand.

Can someone please clarify or suggest a solution?

daba · Jan 24, 2017

The 1734 Point IO only allows 8DI/8DO

For analog you can use 1794 Flex IO...

I've added 2 x 1794-IF4I modules to the configuration to show it works.

free_agent_7 · Jan 24, 2017

Thanks very much.

ASF · Jan 24, 2017

daba said:
The 1734 Point IO only allows 8DI/8DO

For analog you can use 1794 Flex IO...

I've added 2 x 1794-IF4I modules to the configuration to show it works.

Is that just due to the outdated firmware? I'm sure you know that analog cards exist for point I/O

jkerekes · Jan 24, 2017

You can definitely have analog with Point I/O. Also more than 8DI/8DO.

daba · Jan 24, 2017

I only went with what the programming software allowed me to add to the IO config, which is usually a good start.

Perhaps not in this case...

ASF · Jan 25, 2017

Odd. On the same setup (v15 1756-L62) I have heaps of options available.

I'd go with a 1734-AENT and one 1734-IE8C (assuming your analog inputs are 4-20mA). But Flex I/O will work just as well.

Screen Shot 2017-01-25 at 4.01.37 pm.jpg

rdrast · Jan 25, 2017

We stopped using Flex IO years ago, especially for analog, since it is so unreliable. We only use Point IO now, and haven't had any issues at all. I've got Point racks on Ethernet with up to 30 modules with no issues.

jkerekes · Jan 25, 2017

ASF said:
Odd. On the same setup (v15 1756-L62) I have heaps of options available.

I'd go with a 1734-AENT and one 1734-IE8C (assuming your analog inputs are 4-20mA). But Flex I/O will work just as well.

I think its better to go with the 4 channel modules. The 4 channel modules have the terminals available to wire it up without having to use external additional terminals. The 8 channel module doesn't have all the necessary terminals.

free_agent_7 · Jan 25, 2017

Firstly, thanks to everyone for the input!

ASF said:
Odd. On the same setup (v15 1756-L62) I have heaps of options available.

I'd go with a 1734-AENT and one 1734-IE8C (assuming your analog inputs are 4-20mA). But Flex I/O will work just as well.

I'd rather use the Point I/O as well. I have included a screen shot of what I see in L5K. I work with a wide variety of brands, but if memory serves, the EDS files are the content for the "Select Module" dialog in Logix. It shows 1734-AENT/A. Would series B work as well?

I think what confused me a bit is my fault: I was considering 1734-AENTR ( the 2-port version) NOT the AENT. My thinking was that I need to put an HMI in the remote enclosure and I could just use the 2nd port for it rather than adding a small switch.

AENTR documentation at http://literature.rockwellautomation.com/idc/groups/literature/documents/um/1734-um011_-en-p.pdf

"If using the adapter with a 1756-ENBT module, 1768-ENBT module or an
L3xE processor, use the following required firmware versions for these bridge
modules:
• 1756-ENBT firmware version 4.5 or greater
• 1768-ENBT firmware version 2.1 or greater
• L3xE processor firmware version 17 or greater"

Has anyone used the AENTR with an older processor/enbt module with success? If not, I am fine with the 1734-AENT and using a small switch.

Paullys50 · Jan 25, 2017

free_agent_7 said:
I think what confused me a bit is my fault: I was considering 1734-AENTR ( the 2-port version) NOT the AENT. My thinking was that I need to put an HMI in the remote enclosure and I could just use the 2nd port for it rather than adding a small switch.

The 2 port is for DLR (Device Level Ring) networks. Don't think of it just as a 2nd switch port. Probably requires a firmware update to the controller to use.

Stick with the AENT and small switch until you fully understand DLR.

free_agent_7 · Jan 25, 2017

Thanks for the clarification.

Helliana · Jan 25, 2017

Paully's5.0 said:
The 2 port is for DLR (Device Level Ring) networks. Don't think of it just as a 2nd switch port. Probably requires a firmware update to the controller to use.

Stick with the AENT and small switch until you fully understand DLR.

All the AB device level ring components are designed not only for doing DLRs but also for doing linear configurations. Using the 2nd port instead of installing a switch is totally acceptable because basically you are doing a linear configuration with 2 devices. The big downside of linear over DLR is if you lose one point, you lose everything after that point. Since there are only two devices there, there really isn't much risk there.

Personally, i would probably install a switch for programming access and future expandability, but using the 2nd port on an AENTR module will work perfectly fine.

Edit: This is all assuming that the V15 firmware supports the newer AENTR hardware. If your firmware doesn't support it, you will have to flash it up.

Helliana · Jan 25, 2017

From looking at Rockwell website, it looks like the AOP for the Series B versions of the AENT and AENTR both require at least v17. If you are buying new, you may have issues on V15 with either adapter you buy since they will probably be the newest hardware and firmware revision. I'd recommend upgrading your processors firmware if possible.

free_agent_7 · Jan 25, 2017

In case anyone is curious, see this thread:

http://www.plctalk.net/qanda/showthread.php?t=104255

Similar situation to mine.

Thanks all

Logix Distributed I/O Suggestions

free_agent_7

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daba

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ASF

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