Directsoft6 scaling issues

Hi everyone. I am certainly not a pro at PLC programming but can find my way around AB software fairly well. This directsoft is another story. Simple question really. I have an analog input card that I have used an Ibox to set up in the ladder. IT seems that with the ibox in sets the card up as a 12 bit card. I am trying to scale some 4-20 ma inputs for instance 4-20 = 50 150 GPM There are several ways to do this including an ibox in BCD or BIN I have not been able to get any of them to scale properly though. They all look at 0-20 ma not 4-20 ma and this seems to be the issues.

Suggestions ?

Which input module are you using? Have you set up any module jumpers (If your module has them)?
Also, Do you want the reading in BCD or BIN (Decimal)?

Module is F2-8AD4DA-1 a combo module. I am seeing the input when I change current with my meter, just can't get scale right.
Not sure what the advantages are of BCD or BIN I can set the Ibox up do either.

I try to work with BIN whenever I can in Legacy DL. If you set your ANLGCMB box to Binary, and then place your ANSCLB on a rung with an SP1 contact, then you should be able to use K15000 for your High, and K1638 for your Low to get a 12 bit value that ranges from 5000 to 15000 (2 implied decimal places).

I have not used DS6 yet but you should still have the Ibox to set up for your combo card - ANLGCMB. You will set this up to be either a BCD or Bin format and you should use this format for your scaling. You should be able to use the ANSCL (BCD) or ANSCLB (Bin) for your scaling.

Thanks for all the quick help guys. I am using the ibox to set up the card and it works. I can watch the v memory locations and see the values change with a change in current. I have also tried using the ibox for scaling bit this is where the problem occurs. I have a 4-20 ma device rtd transmitter that is scaled 50-150 degrees f. When I scale this in the ibox it doesn't match up. I get 50 degrees at 0 ma instead of 4 ma. I have tried scaling it 0 -150 in the ibox also but that also proves out an error.

You can move your scale out to cover 0-20 even though you are not using it. If my math is right, 1mA is equal to 6.25 degrees (150-50)/16=6.25 . Looks like your scale should start at 25 and go to 150, 6.25x4=25 (0 thru 3mA ranges). Let me know if this works for you?

wrightbenz said:

Thanks for all the quick help guys. I am using the ibox to set up the card and it works. I can watch the v memory locations and see the values change with a change in current. I have also tried using the ibox for scaling bit this is where the problem occurs. I have a 4-20 ma device rtd transmitter that is scaled 50-150 degrees f. When I scale this in the ibox it doesn't match up. I get 50 degrees at 0 ma instead of 4 ma. I have tried scaling it 0 -150 in the ibox also but that also proves out an error.

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If you trust that your sensor produces 4mA at 50 degrees and 20 mA at 150 degrees, then I would recommend using a driver (loop calibrator) to apply 4 mA and 20 mA and see what the raw values are. Use those raw values in your scaling block.

Sometimes the pure math is good enough, other times there is enough variation in the electronics (or the instructions) that working with a calibrator or a loop test instrument is faster and easier and more accurate. It is also going to be useful even if the theory and instructions are correct just to provide a final check of your programming and wiring.