Beckhoff EP3184 - Data Format.

[MogaRaghu]

I am using a Beckhoff EP3184 Analog Input module to acquire data from a temperature sensor which has a range of -50 to + 150 Deg C range and 4-20mA output.

I am using this module connected to a EP9300 EtherCat to Profinet RT gateway ( http://www.beckhoff.be/EP9300/ )

The data from the module is read from the output of the Gateway and has a format like this : ( 3 sample readings shown )
00008F45
00005145
00006245

Does anyone know how to decipher the above readings ? For information the actual temperature is 26 Deg C approx. and the sensor output is 10.2mA.

 

[g.mccormick]

The first number 8F45 HEX is 36677 decimal.

The module states 16bit.
(36677/65535) * 20 = 11.19MA

 

[MogaRaghu]

The first number 8F45 HEX is 36677 decimal.

The module states 16bit.
(36677/65535) * 20 = 11.19MA

Wish life were so simple...!! Looking at the pattern of values, it appears that the MSB is 45 as otherwise the value will be rolling very badly. And normally Temperature is a very slow changing variable. So i think there is some bit manipulation that needs to be done before the final conversion.

 

[MogaRaghu]

Issue resolved !!

OK just got the solution. The Profinet specs define a valid 4-20mA with a range of 0 to 6C00 or decimal 0 to 27648.

So the scaling is ( ActualValue / 27648 ) * 16 tallies with the observed current level of 10.2 mA.

Hope i am correct ??