Knox Video VS-200 - Manual (Page 51)

K NOX V IDEO VS-200 O PERATION M ANUAL
46
9 RS232 PORT
9.1 Connection
Your unit is fitted with a standard ‘D9’ plug or socket allowing it to be controlled from
a computer or other type of terminal or console with a similar interface. Most
computers fitted with an RS232 port, known as a ‘COM’ port, will have a ‘D9’ plug on
them. To enable connection between the two devices you will require one of two
cables as shown below:
D9 connector type
on C2 unit
RS232 cable type required
for linking to PC
Plug – common on earlier C2 units ‘Null-mode’ D9 socket to socket
Socket – common on recent C2 units D9 plug to socket
Should your PC not have an RS232/COM port, it is possible to add an interface card
into the PC to add this facility. Another option you could use is a USB to RS232
converter. Both methods will add a COM port to your PC, although you should be
aware that these generally do not default to being ‘COM1’ which is the default most
RS232 applications will use.
The default baud rate is 57600 with 8 data bits, 1 stop bit and no parity. This baud
rate can be changed in the System menu to suit other programs if need be.
9.2 Communications protocol
The standard communications protocol for your unit is text-based and is detailed on
our website. Also on our website, you can find the Windows Control Panel for your
unit.
The protocol is also bi-directional (unit and computer both send messages to each
other), so that you can send changes to the unit, and it will also respond with any
changes made via alternate methods (front panel buttons, menu changes and infra-
red control). This enables any attached computer to be aware of any changes made
to the unit from an alternative source rather than itself.
What this means is that you can easily find out the exact command to send to the
unit to tell it to perform a certain function. This can be seen by the data that is sent
back to the computer when changing values on the unit. For instance, just by turning
FREEZE on, by pressing the FREEZE button, will cause RS232 data to be sent to
the computer that represents the command required to set FREEZE on. A second
press, to turn FREEZE off, then sends the computer the command required to turn
the FREEZE off.
Note: Any command you send to the unit will be replied to either with an error code
or with the actual changed value. This may be different to the one you sent; for
example, if trying to set a value too high or too low.