Em 231 Rtd Module Ranges - Siemens SIMATIC S7-200 System Manual

S7-200 Specifications
Table A-34 EM 231 RTD Status Indicators
Error Condition
No errors
24V missing
SW detects open wire
Out of range input
3
Diagnostic error
1
Range status bit is bit 3 in module error register byte (SMB9 for Module 1, SMB11 for Module 2, etc.)
2
Bad status bit is bit 2 in module error register byte (SMB 9, SMB 11, etc. Refer to Appendix C.)
3
Diagnostic errors cause a module configuration error. The module bad status bit may or may not be set
before the module configuration error.
Channel data is updated every 405 milliseconds, if the PLC has read the data. If
the PLC does not read the data within one update time, the module reports old
data until the next module update after the PLC read. To keep channel data
current, it is recommended that the PLC program read data at least as often as the
module update rate.
Note
When you are using the RTD module, be sure to disable analog filtering in the
PLC. Analog filtering can prevent error conditions from being detected in a timely
manner.
Open wire detection is performed by software internal to the RTD module. Out of
range inputs are declared and open wire data is reported as burnout data. Open
wire detection takes a minimum of three module scan cycles and can take longer,
depending on which wire(s) are open. Open Source+ and/or Source- wires are
detected in the minimum time. Open Sense+ and/or Sense- wires can take 5
seconds or more to detect. Open sense lines may randomly present valid data,
with open wire detected intermittently, especially in electrically noisy environments.
Electrical noise may also extend the time it takes to detect the open wire condition.
It is recommended that open wire/out of range indications be latched in the
application program after valid data has been reported.

EM 231 RTD Module Ranges

Table A-35 and Table A-36 show temperature ranges and accuracy for each type
of RTD module.
A-82
Channel Data SF LED
Conversion OFF
data
32766 OFF
-32768/32767 BLINK
-32768/32767 BLINK
0000 ON
Range Status
24 V LED
1
Bit
ON 0
OFF 0
ON 1
ON 1
OFF 0
S7-200 Programmable Controller System Manual
24 V Module
2
Bad Status Bit
0
1
0
0
*
A5E00066097-02