Created Date: November 13,2009

Created by: Tinker

Hi Could anybody give me some insight on a simple way to level off or calibrate 4 type K sensors on a F0-04thm card in DL06 plc. I am noticing they are a couple degrees different from each other in ambient room temp. And i have an application where i need precise accuracy. or should i just store in v-mem and minus or add a few points till they are all the same. Any help would be appreciated. Great forum.

Well, your idea sounds a lot like the; " an error of 2"3 °C may be introduced. To compensate for this you can use ladder logic to correct the values " mentioned in the manual, GMTA? However, if you really need "precise accuracy " you might want to consider RTD sensors if you are working within their temperature range.

from the "online manual ":

Ambient Variations in Temperature

The F0-04THM module has been designed to operate within the ambient temperature range of 0 °C to 60 °C.

The cold junction compensation is calibrated to operate in a still-air environment. If the module is used in an application that has forced convection cooling, an error of 2"3 °C may be introduced. To compensate for this you can use ladder logic to correct the values. When configuring the system design it is best to locate any heat-producing devices above and

away from the PLC chassis because the heat will affect the temperature readings. For example, heat introduced at one end of the terminal block can cause a channel-to-channel variation. When exposing the F0-04THM module to abrupt ambient temperature changes it will take several minutes for the cold junction compensation and terminal block to stabilize. Errors introduced by abrupt ambient temperature changes will be less than 4 °C.

Created Date: November 13,2009

Created by: Bob S BN

I have several systems set up to monitor the pre-existing temp controllers.

For the ladder logic compensation, I "LDD " the temp value, "MULD " by the correction factor, "DIVD " by 1000, and "OUTD " to a corrected value vmem location.

The correction factor is a value input from the c-more, and with no compensation would be a value of 1000. Most have needed no correction, and the rest are within 998 to 1002, which is .2 %.

Hope this is what your looking for,

Created Date: November 13,2009

Created by: FACTSTech

rilver,

Please follow this link

http://www.omega.com/techref/colorcodes.html

you will find that the extension wire can be ±2.2°C (4°F) error, this is probably what you are seeing. My FDA customers calibrate at the end of the T/C and subtract or add the error of each of the T/C runs compared to a very accurate standard (NIST). There will not be an error of any significance from channel to channel on the same module. If you are seeing an large error (1°)it is your T/C or T/C extensions.

Created Date: November 13,2009

Created by: rilver

Hi Could anybody give me some insight on a simple way to level off or calibrate 4 type K sensors on a F0-04thm card in DL06 plc. I am noticing they are a couple degrees different from each other in ambient room temp. And i have an application where i need precise accuracy. or should i just store in v-mem and minus or add a few points till they are all the same. Any help would be appreciated. Great forum.