Allen Bradley - Point IO - Power Distribution

[monkey77 0]

I am definitely a newbie in the world of PLC's. So I hope this doesn't sound like a dumb question.

I do the electrical design for PLC's and have only done this for a few short months. I am currently working with a Point IO PLC. This is the first one I've seen. Because of the qty. of input and output modules, we had to add 1734-FPD and 1734-EPAC to boost the power. Easy enough, I get that. I bring power to the 1734-AENTR.....then, do I hard wire to the next module, or are the next adjoining input/outs connected view the internal power bus?

Same question goes for the 1734-FPD and 1734-EPAC. I understand to bring power to those devices, but do I hard wire to the first module or is it automatically connected via internal power bus?

I have done my research before I posted on this site. I think some of the installation manuals for these devices are conflicting., I think that's why I'm so confused.

Thoughts? Does anyone know of a good trusted manual for such a question. Thanks in advance

[pcmccartney1 141]

Yes, the IO Modules to the right get their power via the internal bus, but there is a limit to the amperage.  Therefore, the FPD, which power the modules to it's immediate right.

As for daisy chaining, yes you may, provided the amperage of the feed is sufficient.  But it's any way you want it.  For instance, you might want to segregate power sources for digital versus analog.  You might have a safety PLC and the safety modules.  You might want Digital Outputs to loss source voltage when an E-Stop occurs, so having a contact in the voltage source going to the FPD would have the affect of dropping the 24VDC power to those outputs.

[monkey77 0]

oK, makes sense. When you said "daisy Chaining" - did you mean hard wire daisy chain or internal bus wire daisy chain?

[pcmccartney1 141]

No, from the power supplied to the ANTR to each FPD.

[monkey77 0]

Thank you for your help

[Ken Roach 194]

The best publication to have on hand when designing a POINT I/O system is the Selection Guide:

https://literature.rockwellautomation.com/idc/groups/literature/documents/sg/1734-sg001_-en-p.pdf

Pages 58-62 in particular have some good diagrams that show how the power bus is divided up.

If you use the Integrated Architecture Builder utility to select bills of materials, it does a lot of the power calculations for you as well.

[monkey77 0]

Ken, thanks for your reply. The selection guide really helps. Someone else created this system in the Integrated Architecture Builder utility, therefore I didn't have to figure out the calculations.

I have one final question. In the image I have attached, it shows 12/24vdc coming into the ADN, points 4 and 6. The dark solid lines leaving ADN, points 5 and 7, I assume that I can hard wire from those points to the next expansion power supply EP24VDC? And I assume the dashed lines are the internally connected bus?

 

PLC_POINT IO_SELECTION GUIDE.pdf