Rockwell Automation T8448 Trusted TMR Zone Interface Module - 40 Channel - Manual (Page 25)

Trusted
TM
Module T8448
Issue 14 Apr 10 PD-T8448 25
3.2.3. Rack 3: AI
The AI board returns the field loop voltage measured by the module. This is used for analogue and
digital inputs, and also for monitoring outputs.
Channel Description
1 Field channel 1 voltage
2 Field channel 2 voltage
40 Field channel 40 voltage
Table 9 Rack 3: AI bit descriptions
The voltage is the median value taken from the triplicated module. The voltage level is reported as an
integer, with the units being
1 /
500
V. This may be used directly, scaled arithmetically or scaled using the
IEC1131 TOOLSET conversion tables.
To scale the value arithmetically simply divide the returned ‘integer’ by 500 to return the voltage as
either a REAL or INTEGER as required.
The IEC1131 TOOLSET conversion tables may be used to convert the value to engineering units, in
this case voltage. The full-scale range for this number format is decimal ±64, corresponding to
physical range –32000 to +32000.
3.2.4. Rack 4: CI
The CI board returns the field loop current measured by the module. Note that current inputs sink
current into the 250 ohm resistor on the VFTA, and not into the module.
Channel Description
1 Field channel 1 current
2 Field channel 2 current
40 Field channel 40 current
Table 10 Rack 4: CI bit descriptions
The current is the sum value taken from the triplicated module. The current level is reported as an
integer, with the units being
1 /
1000
A. This may be used directly, scaled arithmetically or scaled using the
IEC1131 TOOLSET conversion tables.
To scale the value arithmetically simply divide the returned ‘integer’ by 1000 to return the current as
either a REAL or INTEGER as required.
The IEC1131 TOOLSET conversion tables may be used to convert the value to engineering units, in
this case current. The full-scale range for this number format is decimal ±32, corresponding to
physical range –32000 to +32000.