Digital Word Map; Rtd Input To Digital Conversion; Figure 2 Word Input To The Plc From The Module; Figure 3 Example Change Input Level - Control Technology CTI 2552-A Installation And Operation Manual

1.3 Digital Word Map

RTD and/or millivolt signals are translated into a 14-bit digital word. Since the PLC requires a 16-bit
input word, the 14-bit value from the converter is placed into a 16-bit word for transmittal to the PLC.
As shown in the following figure, of the two bits not used for the digital word, one is used to show
the sign of the word, while the other is used to note values which are "overrange."

Figure 2 Word Input to the PLC from the Module

1.4 RTD Input to Digital Conversion

The following equations may be used to calculate the digital word in decimal format which will result
from a particular RTD input:
RTD Mode, Digital Word (WX) = Degrees X 10
Millivolt Mode, Digital Word (WX) = Millivolts X 100
As an example, the following figure illustrates the effects of a change in input level going from 0
degrees to 102.4 degrees in the RTD Input Mode.

Figure 3 Example Change Input Level

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CTI 2552-A Installation and Operation Guide