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General => Frequently Asked Questions => Topic started by: support on November 26, 2012, 11:31:19 AM

Title: How to scale SETDAC to Output 4-20mA
Post by: support on November 26, 2012, 11:31:19 AM

The FMD88-10, FMD1616-10 and F2424 PLC supports 0-5V of Analog outputs  which be converted to two channels of 0-20mA analog output using the AN20MA-2.

Assuming variable D may contain values between 0 and 10000 (0.00% to 100.00%) and you want to convert the corresponding value to 4 to 20mA.

1) The output X has to be between (4/20*4096 = 819) and (20/20*4096 = 4096)

       So:    D/10000  =  (X - 819)/(4096-819)
                => X = D*3277/10000+819

2)  Formula:   SETDAC n, 819+ D*3277/10000

Verify:
      When D = 0 => SETDAC n, 819           ' n is the DAC output channel
      When D = 5000 => SETDAC n, 2457
      When D = 10000 => SETDAC n, 4096