Siemens S5-135U/155U - Manual (Page 404)

9-22
System Manual
C79000-G8576-C199-06
9.3.12 Broken Wire Signal
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 1)
0
0
1
1
1
0
0
1) With the 460 analog input module, the value 0 is also encoded for the intact Pt 100 resistances
because the auxiliary circuit is interrupted; the error bit will not be set for these channels.
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 a line of the auxiliary circuit (I
C+
, I
C-
) is interrupted, the “negative range
limit” is encoded for all inputs and the overflow bit is set to “1.” In the event
of a sensor or measuring line open-circuit, the error bit is additionally set to
“1” for the relevant channel.
Broken Wire
Signal in the
Standard Pt 100
Range
Broken Wire
Signal in the
Extended Pt 100
Range
Analog Input/Output Modules