User manual

RS232C Interface Page 13
Columbia Weather Systems, Inc.
Says that DCE is ready to accept data from the Capricorn II. Tied to DCD in some DCE’s.
The Capricorn II will not send data until DSR is active.
8 DCD Carrier Detect To Capricorn II
Says that DCE has detected a carrier. The Capricorn II will not send data until DCD is
active.
4 RTS Request to Send From Capricorn II
When the Capricorn II is ready to transmit data, it raises RTS. RTS is dropped during the
wait period between outputs and upon receipt of an X-OFF.
5 CTS Clear to Send To Capricorn II
Says that the DCE is ready to accept data from the Capricorn II. The Capricorn II will not
send data until CTS is active. CTS may be tied active in some DCE’s.
2 TXD Transmitted Data From Capricorn II
3 RXD Received Data To Capricorn II
Operation as a DCE
To use the Capricorn II Interface as a DCE, you must change the pins at which certain
signals appear by setting the DIO switches accordingly. For instance, a DTE normally
transmits data on pin 2 and the DCE connected to it receives data on pin 2. Conversely, the
DTE receives on pin 3. The same is true of the control signals RTS, CTS, DTR, DSR, and
DCD.
By use of the second set of 8 configuration switches, the user can easily select the specific
connector pin on which each of these signals will appear.
The two signals that a DTE does not normally supply, Data Set Ready (DSR) and Data
Carrier Detect (DCD), have internal pull-up resistors in the Capricorn II Interface, so these
two pins can be left open and do not need to be tied active. The Interface has internal pull-
up resistors on pin 6, DSR, and pin 8, DCD. This feature allows the Interface to fully support
these signals, but eliminated the need to “tie high” these pins if necessary.
Pins in the circuit board are provided for a jumper to be installed if the RTS signal is to be
used again in a different configuration.