The PM8TC module is a 8 thermocouple input module.
The module uses differential inputs to reduce effects of electrical
noise and mains pickup. The thermocoupleinputs are isolated from
the logic. If inter channel isolation is required then the PM8TCISO
should be used.The thermocouple voltage is read by the module
circuitry,linearised and converted to degrees Centigrade. No ranging
is required as the module covers the full range as indicated in the
table of TC types. The value that is read from the Modbus register is
the actual temperature in degrees centigrade to 0.1°C resolution. ie:
a value of 3451 corresponds to a temperature of 345.1°C.
The thermocouple type is setup by writing a value to the TC Type
The value is obtained from the table below. For example to select
type K thermocouples, the value "2" must be written to the TC Type
register. All 8 thermocouple inputs adopt the same TC type.
The DIP switch 9 is used to select upscale or downscale burnout. A
value of 32768 is used to indicate upscale burnout and a value of
-32767 is used to indicate downscale burnout.
The module has built in Cold Junction Compensation. Use must be
made of the correct thermocouple extension wire to avoid reading
errors. The thermocouple module can also be configured for a 0 -
50mV input range.
The TC Type register must be set to 9 for this option. The value in
the register which is read back over the
network is 0 - 50,000.
Note: As there is no inter-channel isolation, isolated thermocouples
must be used in order to prevent ground loops and reading errors.