GE Versamax PLC output module

You can't do it with the IC200ALG320 (4 channel, 12-bit) module, but you could replace it with an IC200ALG331 (4 channel, 16-bit, isolated analog output), an IC200ALG326 (8 channel, 13-bit), or an IC200ALG328 (12 channel, 13-bit). Any of those can be configured for a 0-20 mA range.

Steve Bailey said:

You can't do it with the IC200ALG320 (4 channel, 12-bit) module, but you could replace it with an IC200ALG331 (4 channel, 16-bit, isolated analog output), an IC200ALG326 (8 channel, 13-bit), or an IC200ALG328 (12 channel, 13-bit). Any of those can be configured for a 0-20 mA range.

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Thanks a lot for the answer. I suppose I will have to make programming changes to the software as well? Right now I am taking the real value (%R) and multiplying it by 320 (The output scale is from 0-32000 = 0-100%. The output is based on counts.) and then converting it to an int value (%AQ) and sending it to the DCS. What chanegs do I need to make in the programming? I think 4 channel output module would be sufficient for now. How would the 12-bit (my current IC200ALG320) to 16-bit (proposed IC200ALG331) make a diff?

With the ALG331, a value of 20000 in the %AQxxx register assigned to a channel gives you a 20 mA output and a value of 4000 gives you 4 mA output. If your program logic puts a value of 2000 in the %AQ address, the module will output 2 mA.

I have attached a screenshot of what I have now with the ALG320 module (4-20mA). here the multiplying factor is 320. how would this rung of logic change to output 0-20mA?

Your image is pretty much unreadable, but if you're currently multiplying a variable that can range between zero and 100 to get a value of 0 to 32000 in the %AQ register, You'll need to change it to:

(Percent * 160) + 4000

That will give you 4 to 20 mA corresponding to zero to 100%, the same as the current setup. To output less than 4 mA, use a "Percent" value less than zero.

any suggestions on which of the modules suggested by you would be best suited to replace my existing module?

any suggestions on which of the modules suggested by you would be best suited to replace my existing module?

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The module you're using is limited to 4 - 20 mA range. Any of the three I mentioned are capable of outputting a 0 - 20 mA range.

What are your criteria for making the selection? Cost? Minimum impact on the existing setup? I don't know enough about your system or the constraints you have to operate under to be able to offer anything more than I have already. I've given you three viable alternatives. You know your system better than I. The selection from among those three choices is your call, not mine.

Here's example of impact on the existing system. You have a 4 channel analog module in place. If you replace it with another 4 channel module, then all of your analog outputs can remain at their current address. If you replace the 4 channel module with an 8 channel module, and you have other analog output modules at higher numbered %AQ addresses, then either the existing analog output channels might have to change their addresses or the channels at higher addresses might have to change to accomodate the additional new channels. If the existing 4 channels are the only analog outputs in the system, then this is a non-issue.

As far as cost is concerned, I expect that the ALG320 is the least expensive of the VersaMax analog output modules. I'm sure that the 12 channel, 13-bit module will cost more than the 8 channel, 13-bit module. I'm not sure where the 4 channel 16-bit module fits in the cost structure.

I guess my criteria for selection is minimum impact on the existing setup. and we don't have any other %AQ addresses so adding the 8 channel module shouldn't be a problem, I suppose.