Automation Direct DL405 User Manual page 161

8–12
F4–08THM–n 8-Channel Thermocouple Input
Writing the Control Program
Multiple
Channels
Selected
Automatic
Temperature
Conversion
Since all channels are multiplexed into a single data word, the control program must
be setup to determine which channel is being read. Since the module appears as X
input points to the CPU, it is very easy to use the active channel status bits to
demultiplex the individual channel information
Temperature
Sign Bit
If you are using the temperature scale (°F or °C) then you do not have to perform
any scaling. Once you convert the binary temperature reading to a four-digit BCD
number, you have the temperature.
F4–08THM–n
8pt 8pt 16pt 16pt 16pt
Input Input Input Input Output
X0 X10 X20 X40
– –
– –
X7 X17
X37 X57
V40402
V40400
V40401
MSB
Data Bits
Channel
Indicator Bits
16pt
Output
LSB