Rockwell Automation T8403 Trusted 24V dc Digital input Module - 40 Channel - Manual (Page 18)

Trusted
TM
Module T8403
Issue 15 Jun 13 PD-T8403 18
Value Description
7 Unknown
5 Short circuit
4 Closed contact
3 Indeterminate
2 Open contact
1 Open circuit
Table 7 Rack 2: STATE Output descriptions
The input channel has a value 7 (Unknown) when:
1. The input channel cannot be correctly measured by two or more slices of the TMR input
module.
2. The TMR Processor detects a 2oo3 channel discrepancy between the three slices of the
TMR input module.
3. The module is simulated (not installed or the TMR Processor cannot communicate with 2oo3
slices of the module).
3.2.3. Rack 3: AI
The AI board returns the field loop voltage at the input.
Channel Description
1 Field input channel 1 voltage
2 Field input channel 2 voltage
40 Field input channel 40 voltage
Table 8 Rack 3: Channel Field Voltage
The voltage is the median value taken from the triplicated module. The voltage level is reported as an
integer, with the units being
1
/
512
V. This may be used directly, scaled arithmetically or scaled using the
IEC1131 TOOLSET conversion tables.
When used directly the value may be considered as a signed, fixed-point binary value, i.e.:
Bit
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Sign Integer Fractional
Table 9 Rack 3: Channel Field Voltage bit definitions
To scale the value arithmetically, simply divide the input value by 512 to return the voltage as either a
REAL or INTEGER as required.
The IEC1131 TOOLSET conversion tables may be used to convert the input value to engineering
units, in this case voltage. The full-scale range for this number format is decimal ±64, corresponding
to physical range –32768 to +32767. Other units may be chosen depending on the numeric resolution
and span of the desired result.