NTI VEEMUX AUDIO/VIDEO MATRIX SWITCH
10
RS232 CONTROL
RS232 enables the VEEMUX to be remotely controlled via RS232. To control the VEEMUX via RS232 the user has three
options:
•
write a program that runs on a PC using the Command Protocol (page 11)
•
use the Matrix Switcher's Control Program (page 13) provided on the CD
•
use the SerTest program (page 13) provided on the CD
Remote Connection
The RS232 Interface is designed to control the switch via serial (RS232) daisy chain connection from any host computer or other
controller with an RS232 communications port.
The pin outs for the DB-9 connector on the unit are as follows:
RS232 Connector (DB-9 FEMALE)
PIN
SIGNAL
FUNCTION
1
None no
connection
2
TXD
Transmit Data (RXD at host)
3
RXD
Receive Data (TXD at host)
4
DSR
Data Set Ready
5 GND
Signal
Ground
6 DTR
Data
Terminal
Ready
7
CTS
Clear to Send
8
RTS
Request to Send
9
None no
connection
On the DB-9 female connector, pins 4 (DSR) and 6 (DTR) are shorted and pins 7 (CTS) and 8 (RTS) are shorted. Therefore, host
handshaking is bypassed and TXD and RXD are the only active signals. A straight through DB-9 cable (not null modem) will work
for most CPUs. To daisy chain multiple units, use NTI Matrix-Y-1 "Y" cables, except for the last unit connected. (see Fig 6). For a
pinout of the Matrix-Y-1 cable, see page 45. For straight through cable pinouts applicable to various terminal types, see page
44.
Baud Rate
The unit powers up with a default baud rate of 9600 and a fixed data protocol of 8 data bits, no parity and 1 stop bit. The baud
rate is selectable through the "Baud Rate Menu". A data protocol of 8 data bits, no parity, and 1 stop bit is used in the daisy
chain communication.
Unit Address
To allow multiple units to be controlled from a single host port, the RS232 control interface is designed to allow "daisy chaining" up
to 15 units using the NTI Matrix-Y-1 "Y" cables. By setting the appropriate unit address with the keypad, each unit can be given a
unique address (1-15). Then the unit will only respond to commands on the bus if its address is embedded in the command. (See
Fig. 6.)
Figure 6- RS232 Connections for Daisy-chain
NTI
SWITCH
Host
CPU
RS232
First Unit
NTI
SWITCH
RS232
NTI
SWITCH
RS232
Second Unit
Last Unit
RS232
Serial Port
Matrix-Y-1
Matrix-Y-1
Matrix-Y-1
