Siemens GC..M.. Manual de usuario descargar pdf (Pagina 6)

http://www2.merrick-inc.com/mct/GCMModbus.pdf Page 6 2014-05-18/Lars

You can also use the RS-232 interface if the GCM is the only slave on the line, effectively a point-

to-point connection. The cable must be short, less than 50 feet at 19200 baud. The GCM receives

data on terminal 2 (RxD) with respect to GND, and transmits, after being addressed, on terminal 3

(TxD) with respect to GND. GND is terminal 4.

The RS232 interface also allows for up to 50V common mode swing with respect to the 24V DC

negative terminal on the GCM.

Both ports have LED indicators for receive (Green) and transmit (Red) data. Port 2 LEDs are to

the right on the GCM board.

This picture shows a GCM connected to an

inner point of a 4-wire RS485 multidrop line.

Note that the cable used has two individually

shielded pairs. The drain wire from all four

pairs (two incoming, two outgoing) are

connected to terminal 5, the RS485 cable

ground.

The upper row of terminals is Port 2 (UART1)

and the lower row is Port 1 (UART0).

This picture shows a GCM connected to an

end point of a 4-wire RS485 multidrop line.

Note the terminating resistors.

The master does not have to be an end point

of the multidrop line, assuming you can

disengage the terminating resistors in the

master.

This is an RS232 connection. The shield is

connected to terminal 1, GCM Chassis

Ground. For some hosts, it may be better to

connect the shield to pin 4, RS232 GND.

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Siemens GC..M.. Manual de usuario Pagina 6