4-6
SIMATIC PC RI25/45, Technical Description
C79000-G7076-C808-01
4.3
Temperature Monitoring / Display and Fan Control
The temperature is measured via a sensor (NTC) and its status is indicated
via a green LED for normal temperature and via a red LED for errors. The
following conditions may cause errors:
Overrange of the acceptance limit of excess temperature
Underflow of the acceptance limit of insufficient temperature
Line break or temperature sensor unplugged
The temperature status can be checked at bit 0 of the I/O cell base a
0Eh.
An error causes one of the following reactions:
Reaction
Option
TempLED changes from GREEN to RED
always
Canceling of TempBit in I/O cell base a 0Eh
always
Relay output falls in quiet state
always
Initiate IRQ
can be set
Note
The NTC is a separate component and only connected to the monitoring
module via a plug connector. The NTC is equipped with cable and connector
and is part of the list of components. In order to guarantee correct
temperature monitoring, an NTC with a resistance of 10 kOhm is required
(SBS Order No. 57703-M103-G).
The NTC resistance is commuted to a SafeCard connector via twisted pair
cable. The errors “line break” and “connector unplugged” are additionally
monitored by open-circuit monitoring. A line break is signaled by a
temperature error.
Temperature
Monitoring
Monitoring Line
Break
Monitoring Module