DL205 Analog Manual, 7th Edition Rev. D
7-17
Chapter 7: F2-04THM, 4-Channel Thermocouple Input
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Negative Temperatures 2’s Complement for the DL240, DL250-1 and DL260 CPUs
(Binary/Pointer Method)
The 2’s complement mode used for negative temperature display purposes, while at the same time
using the magnitude plus sign of the temperature in a control program. The DirectSoft element
Signed Decimal is used to display negative numbers in 2’s complement form. To find the absolute
value of a negative number in 2’s complement, invert the number and add 1 as shown in the
following example:
Understanding the Input Assignments (Multiplexing Ladder Only)
Remember that the F2-04THM module appears as a 32-point discrete input module to the
CPU. Use these points to obtain:
• An indication of which channel is active
• The digital representation of the analog signal
• Module diagnostic information
Since all input points are automatically mapped into V-memory, it is easy to determine the
location of the data word that will be assigned to the module.
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LD
V2000
OUT
V2010
ADDB
K1
V2000K8000
²
INV
Loadnegativevalue into theaccumulator so we
canconvertittoapositivevalue.
Invert thebinarypattern in theaccumulator.
Add1.
Save Channel1dataatV2010.
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