Connection and layout data

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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 9-18 volts @ upto 160mA per module
LED disable  Low - tally lights enable
High - tally lights disable

Power supply considerations:

Power Supply: (Pin 5) The module requires a 9 to 24 VDC power supply. We recommend that a supply of less than 18 volts be used unless a higher voltage is needed for other reasons. A fully loaded module draws up to 160 mA. The power inputs are isolated from the output and frame ground. The power supply must be fully line isolated and the 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.

Distribution Cables:

Data cables should be shielded twisted 120 ohm pair rated for EIA485 uses at 250 kilo-baud. The shield is not current carrying and must be connected to power supply common only once in a system, usually at the power supply. Power cables must be sized to ensure that when voltage drops on both the supply and common lines are included the power to the module remains above seven volts at all times.

In many cases Cat5 or better Ethernet cable can be used. Unless the cable is run in metallic enclosures, shielded Cat5 is preferred.

Voltage Drop

Another VERY 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 two volts and a positive common mode limit of 12 volts. Ground return drops of greater than five volts should be avoided. Ground return drops of more than eight volts will cause unreliable operation. See the page on figuring the voltage drop.

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 output.

The  voltage level on pin 6 of the module determines if the tally light is enabled. If the line is high (2.7 V 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.

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

installed = disabled
remove =  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


  More technical data is available  in PDF form

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

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