nogz (Customer) asked a question.
P1AM-100 with P1-04THM Thermocouple module reporting inaccurate temperature readings?
My team is doing a heating application using these P1-04THM cards to monitor J-type thermocouples and turn some solid state relays. However, we are getting lower temperature readings, sometimes off by 100 degrees F, compared to a calibrated pyrometer the company uses to verify temperatures. Our configuration string is as follows:
- const char _PBVAR_1_ConfigureP104THM_6[] = {0x40, 0x03, 0x60, 0x07, 0x21, 0x00, 0x22, 0x00, 0x23, 0x00, 0x24, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
- const char _PBVAR_2_ConfigureP104THM_7[] = {0x40, 0x03, 0x60, 0x07, 0x21, 0x00, 0x22, 0x00, 0x23, 0x00, 0x24, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
- const char _PBVAR_3_ConfigureP104THM_8[] = {0x40, 0x00, 0x60, 0x07, 0x21, 0x00, 0x22, 0x00, 0x23, 0x00, 0x24, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
We are looking for high side burnout type j. The last card has jumpers on the un-used channels.
sounds like to me your thermocouple attached to the plc is going out or for some reason on the plc program the thermocouple is set to the wrong type than you are running, my suggestion is my suggestion is to check program on plc and make sure program is set to j type thermocouple, then heat your heater element up to temp and record reading your plc is displaying, then unplug thermocouple module and disconnect thermocouple wire and attach wires to handheld thermocouple meter to see if your getting the same readings on j type setting, that will tell you if its the thermocouple or the plc program
Have you tried verifying the modules or thermocouples?
One thing you can do on the module is jumper all the channels and check the readings. It should read the ambient air temperature.
Edit: Also if possible could you post the code. Use the code snippet button that looks like </>.
Are the thermocouples ungrounded junctions?