Display And Control Elements - W&T Electronics RS232 Handbuch

W&T
RS232(/422/485) Universal Serial T-Switch
The terminating DIL switches SW6 and SW7 must never be in
the ON position when using the module in RS232 mode. This
will result in a significant increase in the current draw and may
cause the RS232 driver to fail.
Termination
All RS485 modes require termination of the bus system with a
termination network. The resistor combination integrated in the
module performs two tasks in RS485 applications:
1. The connected line is terminated corresponding to its
impedance, which prevents signal reflections at the cable end.
2. In the high-impedance phases of bus operation a defined
quiescent state is ensured.
The bus system is allowed to be terminated with the terminati-
on network only in RS485 and RS422 modes, but not in RS232
mode.
Closing DIL switches 6 and 7 on the Interface Module
c o n n e c t s t h e b u s t e r m i n a l s t o t h e r e s i s t a n c e
network.

Display and control elements

The device uses four LEDs, a green „Power" for indicating
correct supply voltage and the LEDs marked „A" and „B" to indi-
cate which input channel is active.
The LED marked „Error" indicates the presence of parity or
framing errors in running data traffic and can only be
cleared explicitly by pressing the „Clear" key. The „Clear" key
resets the T-switch and deletes all internal data and error
memories.
Pressing the „Dump" key when the device is turned on
outputs the current setting of the T-switch on whichever
serial port has been selected using the DIL switch.
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Subject to error and alteration