Rev D
Model MS-500x
CrossPoint Technologies, Inc
4
5
4
3
2
1
9
8
7
6
5
4
3
2
1
9
8
7
6
9 pin female D connector
9 pin female D connector
Figure 2 : PC to Matrix Chassis
– RS-232
The Serial port connector (CTRL) pin assignments are:
Pin
RS-232
Applicability
RS-485
Applicability
Circuit Function
Direction
1
X
TxDataB
Output
2
X
Receive Data
Input
3
X
Transmit Data
Output
4
X
RxDataB
Input
5
X
(Shield)
Gnd
6
X
TxDataA
Output
7
unused
8
unused
9
X
RxDataA
Input
3.2
RS-422 Remote Control Operation
RS-422 operation allows data communication over cables of up to 4,000 feet. Use RS-422 when
the remote computer must be located far from the matrix chassis, or when ambient electronic
noise levels are very high. The RS-422 standard uses balanced differential signaling, for
significantly more reliable communication than RS-232. The drivers and receivers are RS-485
compliant, which makes them suitable for direct interface to full duplex RS-485 systems as well.
The link can operate at four baud rates between 2400 and 19200 bits per second. The other
communication parameters are fixed at 8 bit words, no parity and 1 stop bit. Set your remote
computer interface to the same settings. For long runs, a termination might be required to assure
reliable communication at high baud rates. If you experience data integrity problems (parity errors,
garbled data) try slower baud rates. If slower baud rates help, then try the faster rates with a 120
ohm terminating resistor across the receive data pins (RXA and RXB). Terminate each pair at its
receiver. The terminations can be installed inside the back shells of the cable connectors. The
actual resistance value may be adjusted to match the cable’s characteristic impedance. A value of
120 ohms is typical for twisted shielded pairs.
The serial interface does not support hardware or software flow control. Commands and
responses are relatively short and flow control is not normally required. The command/response
method assures that the host computer can sense if the Matrix is unable to accept more
characters.
