User Guide Owner's manual
Coms
RS-232 pass-through
The Coms port on the rear panel of the encoder (see figure 6,
R
on page 13), or decoder
(see figure7,
R
on page 13) is used for RS‑232 pass‑through communications, allowing
a control device connected to one VNM 250 unit to control a remote device connected to a
second VNM250 unit.
Serial data received by one VNM 250 unit is transmitted over the network, using
TCP/IP, and then converted back to serial data at the target VNM 250 unit. Data flow is fully
bidirectional.
Units that are configured for this type of data flow are called pass-through groups:
z One device in each pass‑through group is designated as a server.
z One or more devices are connected as clients.
z There may be more than one pass‑through group in a system.
z A pass‑through group may consist of all encoders, all decoders, or a mixture of both.
z A device may be a server or client independently of whether it is an encoder or decoder
and independently of whether or not it is the system controller.
z Pass‑through data is not part of the media stream and cannot be stored by a
VN‑Matrixrecorder.
z Data passes through the system unchanged (transparently). No VNM 250 devices are
affected by the commands.
z The serial ports on different devices do not need to share a common baud rate.
However, if a large amount of data is sent from a high speed to a low speed data link,
some form of handshaking or flow control may be required to prevent buffer overflow on
the output device. Standard flow control methods are fully supported.
To set up the RS‑232 pass‑through group:
1. Decide which VNM 250 unit will be the server in the pass‑through group and which will
be the clients.
2. Connect your serial devices to the VNM 250 RS‑232 ports
accordingly. Communication can only take place between server
and client, not between clients.
Use the first three poles of a shared captive screw connector
(Tx, Rx, and G). See the Attention and Note boxes on page 14
for information about preparing and connecting wires to a captive screw connector.
3. Log in to the web interface (see VNM 250 GUI Login on page 33).
4. Configure the server (see Pass-through Coms Server Configuration on page 90).
5. Configure one or more clients (see Pass-through Coms Client Configuration on
page 90).
Tx Rx
PASS THRU CONTROL
GTxRx
COMS
CONTRO
L
Tx
Rx
VNM 250 • Rear Panel and Connections 18