Host Engineering Forum

General Category => Do-more CPUs and Do-more Designer Software => Topic started by: Bobby on May 09, 2015, 02:39:53 PM

Title: Simple Analog Question.
Post by: Bobby on May 09, 2015, 02:39:53 PM

Hello all!!

  I am still new to PLC programming and am working on my first project using a do-more plc. I have a 16 bit analog card in my rack. I understand that the resolution of that card is 65,536. My former training taught me that 0=0volts and 65,536=10volts for example. But with the do-more is shows the range being -32768 to +32767. Does that just mean the -32768 would read out a 0 volts and that +32767 would read out 10 volts? (or 5 depending on the settings I guess). Also if that is correct why do it like this? Is there a benefit that I do not see?


Thanks,

Bobby

Title: Re: Simple Analog Question.
Post by: plcnut on May 09, 2015, 03:36:35 PM

It sounds like your module is set up for bi-polar (-5 to +5vdc). If you set it for uni-polar then it should be 0-65535.

Title: Re: Simple Analog Question.
Post by: BobO on May 09, 2015, 11:13:18 PM

The analog data types, WX and WY, are signed by default. If you need 16 bit unipolar, you need to append the unsigned cast operator, e.g., WX0:U.

Title: Re: Simple Analog Question.
Post by: LWgreys on May 17, 2015, 07:09:45 PM

Which analog module do you have?