9.5.10
Broken Wire Signal for
Resistance Thermometers
An open-circuit in the lines to a resistance thermometer is indicated as
follows:
Broken Wire at
Module Reaction,
Encoded Value
Error Bit E
M+
M-
Pt 100
I
C+
I
C-
0
0
0
0
0
1
1
1
1
1
If the mode "without broken wire signal" is selected on the module, an
open-circuit of the resistance thermometer is indicated with an
overflow.
Unassigned channels can be used for voltage or current measurement
if the current flow outputs relating to the particular measuring channel
are shorted with a wire jumper. Without this jumper, the error bit
would be set for this channel and the value 0 would be encoded.
Broken wire monitoring
When set to "resistance thermometer", switch 7 of mode switch I of
the 465 analog input module allows broken wire monitoring of the I
C+
lines to the resistance thermometer (Pt 100 constant current supply).
In the event of open-circuit of this line, the error bit is set as for the
other lines.
At the "voltage/current" (mV/mA) setting, the I
C+
lines are not
monitored for broken wire. (The error bit is not set for an open-circuit
of this line.) You should choose this switch setting if you exclusively
measure voltages or currents.
9
The 465 Analog Input Module
System Manual
C79000-B8576-C109-03
9 - 69
