Rail-Contact User Guide
Page 5
Connections
Contact Closures
Please refer to the connections diagram.
The contact closures are attached via eight
2-pin screw terminals.
DMX512 Output
The DMX512 output is attached via a 3-pin
screw terminal.
DMX512 Input & Loop-Through
If two Rail-Contact units are connected
together to provide 16 channels of triggering,
the DMX output from the first unit should be
connected to the DMX input of the second
unit.
A passive loop-through connection allows
onward connection to other DMX512 devices.
If this feature is not required then the signal
must be terminated. The product contains an
internal termination resistor. This is enabled by
fitting a wire link between the screw terminals
that will terminate the DMX line (Term and
DAT+).
Voltage Output
The single-pin screw terminal voltage output
allows easy connection. The voltage output
pin will be the same voltage as the power
input. It is current limited to 250 mA by an
electronic auto-resetting fuse.
It can be used as the positive supply to the
opto-isolator inputs if the isolation feature is
not required.
Rail-Contact monitors the state of the 8 contact
closures and translates this into a value on
DMX channels 1 to 8. When a contact closure
is active the corresponding value is DMX is
255.
If two Rail-Contact units are linked in series,
the first 8 channels are re-patched to channels
9 to 16.
It is expected that in normal usage, the
opto-isolated inputs will be used to provide
protection from electrical noise arising from
long cable distances to powered equipment
(see Figure 1 in ‘Wiring Diagrams’).
However, Rail-Contact also provides a voltage
output which can be used when connecting to
local volt-free items - such as switches (see
Figure 2 in ‘Wiring Diagrams’ and ‘Voltage
Output’ in the ‘Connections’ section).
Summary of Key Features
y
8 opto-isolated contact closures
y
8-channels of DMX512 triggering
y
Units can be linked to provide 16 trigger
channels
y
Inputs are fully opto-isolated
y
Voltage output for easy connection
y
LED indication for data in/out & power
y
DIN-rail or surface mount
Operation
The 8 contact closure inputs each have 2
terminals labelled Con+ and Con-. Internally,
these connect to the LED of an opto-isolator
via a current limit resistor.
The current limit resistor is set to limit current
to the range 10 - 17 mA over a range of input
voltages of 9 - 24 VDC.
When the voltage is applied, current flows
through the opto-isolator and a full (255) DMX
level is transmitted on the associated DMX
output channel.
Power
Rail-Contact is be powered from an external DC
power supply (9-24 VDC). It is recommended
that a ferrite core be fitted onto the DC power
lines as close as possible to the Rail-Contact.
This protects the unit from any electrical spikes
that appear on the DC line.
LED Indication
Rail-Contact has LED indicators under the
terminal guard for data in (green), data out
(yellow) and power (red).
