MicroLogix 1500 Analog Output

[mhowasso 5]

Hi All.... Im using a MicroLogix 1500. The Analog Input card I am using is a 1769-IF4I. The Analog Output card I have is a 1769-OF4. I need to get both a PLUS 0-10vdc signal AND a MINUS 0-10vdc output signals using only a PLUS 0-10vdc signal in. What is the best way to program this and are there any examples on this here at this site..??? As always, thanks.

[Bob O 8]

So do you need -10 to +10 VDC out?

[Michael Lloyd 85]

The SCP function will let you do whatever you need to do... But if you don't want to use an SCP: Set the data format for the input and output channels that you are using to Scaled for PID If you need a negative number then you can subtract the I register from zero and put the result in the O register. If you need to invert the Input register but represent it as a positive value in the O register Like so: 16384 to 0 = 0 - 16384 Then you need to do the subtraction I mentioned above but put the result into an intermediate register then use the ABS function on the intermediate register and place the value in the O register. Edited 12 Jan 2011 by Michael Lloyd

[mhowasso 5]

I need two outputs. one that is 0 to +10vdc one that is 0 to -10vdc

[Mickey 71]

Post your .rss file so we can see how you have the input and output cards configured. Also where the cards are placed. Then someone can give you an example. As others have said the "SCP" instruction will do what you want. Edited 13 Jan 2011 by Mickey

[mhowasso 5]

Here is the file. Look at the end of the AXIS file for the SCP Outputs for Slot 6 Channels 0 & 1 Thanks 7891049_SACEM.RSS

[Bob O 8]

I think you need to check your SCP numbers for your outputs Here is a sheet that should work for the card..if not someone will come along and correct me. 1769-Of4VI.pdf

[Bob O 8]

Edit added another page 1769-Of4VI Second page.pdf

[Mickey 71]

With the way you have your output card setup ( channel 0 0 to10 volts, channel 1 -10 to +10 volts) see revised SCP instruction below. Note, output destination is the output word for the card in slot 6.

[mhowasso 5]

Oops...Yes, I see, I typed an I not a O. I see how the MOV would work also, but if I wanted, could I use two SCP instructions with one using O:6.0 and the other O:6.1 ??? Should I use 0-10vdc in the card config or use -10 to +10vdc ??? Also, on the O:6.1 can I use a negative number for the MIN or MAX out, or should I just invert the wiring on that channel..??? I dont see in the data sheet the use of negative numbers. I know that Im probably making this harder than it is, and Im sorry, but I just want to make sure I understand. Thanks

[Mickey 71]

Yes, you can use two SCP instruction if you want. The way you have the cards setup will work just fine. If you change them then you will also have to change the scaling in the SCP instructions. Negative numbers would not give you the correct results from your output cards.

[mhowasso 5]

Thanks..!!

[Mickey 71]

Your welcome, let us know how it all works out.