mains pickup. The thermocouple inputs 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 register .
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.