90-30 Expansion Questions

As mentioned earlier in this forum, I'm doing early planning for putting together a PLC system totaling about 100 inputs and 150 outputs. It seems that a 90-30 system would be a suitable low-cost choice (this is a hobby application) due to the abundance of 90-30 hardware in the surplus market.

It seems that small 5 slot units with 311 CPU's or similar are very common but the larger CPU's are not. Since I would be "growing" this system slowly from about 30 I/O to full size, I am tempted to buy multiple 311 CPU systems as needed.

My question is: is there any graceful way to get multiple small processors to coordinate and pass data between them so I don't have to repeat inputs and outputs between the various units thereby swelling my total I/O count beyond the 250 I/O stated above?

If the answer is yes, what extra hardware would I need to watch for to do the inter-communications?

Or, am I just stuck with getting two 10 slot racks and a 331 processor or larger and building I/O on that?

How about that for a nice basic type question from a novice? (No, I'm not a student!!!) Thanks in advance everyone. I appreciate any replies.

First, the model CPU311 or CPU313 units are not expandable. There are five slots available for I/O modules, but you can't add expansion racks to them. You can get discrete I/O modules in 8, 16, or 32 points per module, so you could get a maximum of 5 x 32 = 160 total discrete I/O points in a CPU311/CPU313 system. There are also a couple of modules that are incompatible with the CPU311/313. The most important of these is the IC693CMM311 communications coprocessor module. There is also a 10-slot non-expandable version CPU323, as well as an obselete 10-slot CPU321. All of these models have the CPU embedded in the rack so it doesn't take up one of the I/O slots.

CPU model numbers above 331 are modular CPUs, where the CPU takes up one of the slots in the rack. You need to be sure you get the correct rack part number. There is a 5-slot CPU rack and a 5-slot expansion rack; also 10-slot CPU and expansion racks. CPU331, CPU340, and CPU341 can handle a maximum of 4 expansion racks. CPU models 350 and higher can handle a maximum of 7 expansion racks.

If you are planning to use VersaPro or Cimplicity Machine Edition programming software, you need to watch the firmware revision level of the CPU. There are problems interfacing between VP and older revision levels. The specific version lavels for each CPU model can be found on the tech support website.

To get 100 discrete inputs and 150 discrete outputs would require at least four input modules and five output modules. That would be a full 10-slot rack with a modular CPU.

There are network options to pass data among multiple CPUs, each running its own program. The easiest would be the IC693CMM302, enhanced Genius communications module. A single Genius network can have as many as 32 nodes, and each node can broadcast up to 1K bytes of data. The Genius network cable is very similar to AB's 'blue hose'.
You can also put an ethernet module in each 90-30, DeviceNet, or Profibus.

The GE SNP (System Ninety Protocol) can be used to connect several PLCs together on a network. The message instruction is fairly easy to use.

to Tom Jenkins

Tom, does SNP work with 311 CPU's in 5 card racks?

Dick,

The programming port on the CPU311 is an SNP slave. You would need an SNP master somewhere to exchange data serially among several PLCs. The SNP protocol does not have a peer-to-peer mode.

Thanks everyone. Sounds like I'm stuck with a 331 CPU and two 10 card expansion racks. Oh, well. Didn't hurt to ask, I guess!

My question is: is there any graceful way to get multiple small processors to coordinate and pass data between them so I don't have to repeat inputs and outputs between the various units thereby swelling my total I/O count beyond the 250 I/O stated above?

Click to expand...

Maybe I buried the answer to your question in all of the other information.

If you leave one slot available for an IC693CMM302 (Enhanced Genius Communication) module in each of your CPU311s, your expansion plan will work fine. The CMM302 is pretty easy to configure.

Over the course of the project, you'll spend less money by going with a CPU331 and expansion racks, since each CMM302 costs roughly the same as a CPU331. That's based on the cost of new equipment.

IC693CPU331 Obsolete

You will want to use the IC693CPU350, which is the replacemant for the CPU331. It is faster, has more memory and costs less. The only draw-back, if one could call it so, is that you will need a more recent software version of LogicMaster. If anyone is still using LogicMaster, the older DOS software, I suggest that you upgrade to the latest Cimplicity Machine Edition, Logic Developer PLC.

To Russ B

Russ, since I am likely dealing with the surplus/used market to keep costs down, I may very well have to use a 331 rather than a 350.

Am I trapping myself somehow (maybe software or something else) if I choose the older CPU?

I've narrowed my choices up to now to either a Series One/TI305/ Automation Direct 205 system or a 90-30 system, both acquired, as much as possible as surplus/used. Naturally, I am concerned about buying a "clunker" since I am not up to speed like I should be on PLC equipment and software. I have relied primarily on advice in this forum and will always be grateful for it.

I don't think you have said whether or not you are going to go with Versapro, Cimplicity Machine edition or Logicmaster 90. If you go with Logicmaster you shouldn't have a problem with the firmware level of your CPU. If you go with one of the other two you might have a problem but you can upgrade the firmware to a newer version in order to be able to use those. It costs about $100 and you have to take the CPU apart and replace an EPROM. You can usually find some old stuff on Ebay, although I just looked and there isn't anything good today.

This guy also has sold some stuff on Ebay and deals with used GE so you might want to give it a look.

http://andrewsmachine.mystarband.net