Meinberg DCF77 UA509 - Manual (Page 8)

8
Serial Interfaces
Two independent asynchronous serial ports can be used to transmit information on
date and time to other devices. Each of the ports can be set up as either RS232 port or
20mA current loop port. Baudrate, framing and mode of operation can be configured
separately for both interfaces COM0 and COM1 by DIL switches. Additionally, a
time zone can be assigned to each port: The drivers can be configured individually to
transmit either standard time (MEZ/MESZ=CET/CEST), standard time with suppres-
sion of daylight saving (always MEZ=CET), or UTC. The format of the time string is
described in the section "Technical Specifications".
Outputs
All outputs of one interface (e.g. COM0) distribute the same time string and can be
connected simultaneously. When using the port in the RS232 mode no additional
supply voltage is necessary. The required ±10V are generated on-board.
When using the port in the 20mA current loop mode the additional supply voltage
of -15V is not essential either when using only the passive outputs or a lower
interference immunity is tolerated. In the second case the negative output lines have to
be connected to GND.
Inputs
Only when using the output mode "on request" the RS232 input or the 20mA current
loop input has to be connected. It is not possible to connect both inputs. The jumpers
JP0 and JP1 assigned to COM0 and COM1 have to be set, either to the RS232 input or
to the 20mA current loop input as described on the board (RS = RS232; CL = Current
Loop).
The 20mA current loop input can be driven passive or active (see Rear Connector
Pin Assignment). It is possible to drive the active input without the -15V supply
voltage by connecting the "-akt_in" pin to GND.
Although RTS and CTS handshake lines are provided by the RS232 interfaces, in
most cases they need not to be connected. Due to pullup resistors, the serial outputs are
enabled if the pins at the rear connector are left open.