Connection and layout data - REVISED

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Module Pinout
Pin Function
DMX RF Shield Not current carrying
Circuit Common PS return and 0 volt ref.
Data Minus
Data Plus Data
Power supply 9-30 Volts -24 VDC  ideal   38mA @ 24 volts DC
LED disable  Low - tally lights enabled
High - tally lights disabled
Power Supply Requirements

Power Supply: (Pin 5) Each module is powered by 9 to 30 VDC. (We recommend  24 volts be used.)  At 24 volts a fully loaded module draws less than 40mA. As the power supply voltage decreases, the current requirement increases. The power inputs are isolated from the output and frame ground. The power supply must be fully line isolated and the low voltage common should be DC grounded only at the supply.

Power Supply Common: (Pin 2) The power supply common must be a separate conductor that is not connected to the shield except at one point, usually the system power supply.

The time you put into thinking about cabling before you order material is an investment in your project turning out well.  Many installations can use one type of cable to carry both power supply and the DMX/RDM data.  The most commonly used cable types are 120 ohm 485-style twin pair cable (AWG 22) or CAT5 ethernet data cable.  Often a single run of cable will handle the data and power supply needs of your system.   Example 1 - a system of 32 modules, with between-module spacing of 8 ft, run on CAT5.  Put a 24 VDC power supply at the first module, and use the non-data wires in the CAT5 cable for power supply and ground.  Example 2 - a system of 24 modules, with between-module spacing of 20 ft between each pair of modules, can be run on standard 485, 22AWG cable.  Put a 24 VDC power supply at the first pair of modules, and use the non-data pair for power supply and ground. Many other systems are easily accommodated, including ones with the power supply remoted to a control closet/room. Please contact the factory.

Voltage Drop:
 An important parameter when sizing distribution cable is the voltage drop on the power supply return (common) wire. Any drop in the common return appears as common mode voltage on inputs to these modules. EIA485 has inherent common mode voltage of about 2 volts and a positive common mode limit of 12 volts. Ground return drops of greater than 3.5 volts should be avoided. Ground return drops of more than 6 volts are undesirable and could cause mis-operation. Please consult the factory.

Cable Selection:
The choice of cable type depends on several factors.  The simplest wire to install is the two-pair 485 cable.  At the worst, two wires will need to be terminated under a single clamp.  In other installations, lower line resistance can be had by paralleling conductors in a CAT5 cable.  In this case, multiple conductors will need to be terminated to carry the ground and power supply.  There are several ways to handle this; please consult the factory.  CAT5 cable is well understood by low-voltage datacom installers.  Unless the cable is run in metallic conduit, shielded CAT5 is preferred.

Jumper Settings

There are a number of internal jumpers on the modules. The units are shipped with the default jumpers installed. In most cases the installer only has to properly configure J8 and J9. The modules on either end of an internal network segment (daisy chain) will have them installed; other modules will have them removed.  It does not matter whether that module is an input or an output.

The  voltage level on pin 6 of the module determines if the tally light is enabled. If the line is high (2.7V to5 V)  the front panel tally is disabled.
If the pin is grounded (-0.2V  to 0.8V) the tally light is enabled. If Pin 6 is left open, the state of the tally light is set by jumper J7.

If the system is wired with CAT5 cable, one conductor in the cable can be used for tally light control.  If 2-pair cable is used, a separate conductor would be required.

Module Jumpers



XLR Terminate Enable

Output modules have J1 & J3 installed. Input modules with loop thru have them removed. Other input modules have them installed.



XLR Terminate Enable



Grounded Port

Installed on output ports wishing to follow DMX512-A grounded transmitter topology.



Tally light default

J7 installed - Controlled by  pin 5
 Low = enabled -- High - disabled
J7 remove - Always enabled



Internal bus termination

Install J8 & J9 on units on either end of the network, Remove J8 & J9 on all other modules.



Internal bus termination


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Goddard Design Company - 51 Nassau Ave. - Brooklyn NY 11222 USA
718 599-0170 718 599-0172 fax -

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