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9.1 RS-232-C system bus interface
The system bus connection is located at the back of the controller housing (RJ-12 jack).
In this case, the controller can be connected either directly to the serial interface of a PC
(point-to-point connection) or to a (dial-up) modem. A dial-up modem is required if the control-
ler is to be connected to the telecommunications network. In this case, the controller works au-
tonomously and can issue an alarm call to the building control station when errors occur. Addi-
tionally, the building control station can dial up the controller, read data from it, and send new
data once the valid key number has been written to the holding register no. 40070.
On recognizing the key code from the controller as valid, the register value “1” confirms writing
permission. In any other case, the register value remains at “0”. Any further establishment of
communications requires the writing permission to be acquired by resending the key number.
Note!
If a wrong key number has been written to holding register no. 40070 for the third consecutive
time, the controller immediately interrupts the modem connection and sets the D6 bit of the error
status register (Unauthorized access). As a result, the call to the configured control system is
triggered or a text message/fax is sent. Bit D6 is deleted as soon as the error status register has
been read by the control system and the connection has been terminated.
In special cases, the Lock dial-up function can be selected to stop dial-up in case of faults. Using
the Dial-up also upon corrected fault function, the controller additionally informs the building
control station when a previously registered fault no longer persists.
EB 5179 EN 77
Communication
GND TD DTR RTSRDDCD
Fig. 8 · Pin assignment of RJ-12 system bus interface