DMX USB RX A8

Introduction
The DMX-USB-RX-A8 module is a fully compliant with the latest USITT DMX512-A standard, E1.11-2004. This small module, powered by a single 18VAC supply, provides 8 analogue outputs.

Features
Fully compliant with the latest USITT DMX512-A standard.
Backwards compatible with the older USITT DMX512/1990 standard.
Easy to use configuration via a USB port. PC application supplied, no dip switches to worry about.
Uses a single isolated 18VAC supply for power.
Module can be set to any DMX address from 1-504 .
Output ranges may be individually set from 0 to +/- 5v, up to 0 to +/-15v
DMX feed though on all pins, including 4 & 5.
Selectable 120 Ohm termination.

Connections
Power can be connected to the module either from an 18v AC transformer to the two pin screw terminals, or from an 18v AC adapter. This must be an isolated supply: do not use the same supply for more than one module. The module cannot be powered from the USB port. The 120 ohm terminating link connects an on-board 120 ohm resistor across the DMX. This should only be fitted to the last module on the DMX cable. Remove the link on ALL other modules.

Getting Started
The default factory settings for your DMX-USB-RX-A8 module is DMX address 1 and 0 to +10v outputs. If this is what you need, then just connect the 18VAC supply, plug in the DMX cable and your away.

It's more likely that you want to select a different DMX address and to change the output voltages. To do this you will need a PC running Windows XP/Vista/Win7.
You will need:
The DMX_A8 Configuration program.
The USB driver for windows.

Run the DMX_A8 Configuration program, and you will see the following dialog. Select the new comm. port and it will find the module and display its software revision number. The DMX address the module is currently set to is displayed and the calibration values.

Changing the Output voltages
Important - Disconnect the DMX cables before you do this. Incoming DMX will corrupt the calibration.
To change the output voltage from the factory default 0 to 10v range, you will need volt meter (multi-meter). Connect this to the 1st channel you wish to modify. The first thing to do is to set the zero voltage level. Click the "Zero" button. Note that all the DMX levels have changed. They are no-longer the DMX levels, but internal calibration values. Note also the "Clear" and "Store" buttons and Sliders have become active. Using the sliders adjust the level on the multi-meter to read as close to 0v as possible. You should be able to get within 8mV of 0v. The zero volt calibration is only done once and affects all channels. It can be done on any channel.

Now the maximum output can be set. Select the channel you which to calibrate, and adjust the coarse and fine sliders. You should be able to get within 8mV of your target. Repeat this for each of the outputs. When you have finished, check and change the DMX address if required, then click "Store", this will save the new calibration data in the non-volatile memory on the DMX-USB-RX-A8 module. Disconnect the USB cable and re-connect the DMX cable.

When you press "Store" (or "Clear" to discard changes), The dialog will revert to displaying DMX levels:

Changing the DMX address
The DMX address can be set to any between 1 and 505. Just enter the new address in the "DMX Addr" edit box and click the "Update Address" button. The 8 channels on the DMX-USB-RX-A8 module are numbered consecutively. If you select address 505, then channel A1 will be at address 505, channel A2 will be at address 506 and channel A8 will be at address 512.

Use	5-pin XLR Pin number	DMX512 Function
Common Reference	1	Data Link Common
Primary Data Link	2	Data 1-
Primary Data Link	3	Data 1+
Secondary Data Link (unused by module, but connected through on XLR's)	4	Data 2-
	5	Data 2+

Termination
If the module is the last one on the DMX cable, you should ensure the link is fitted on the board. This will enable the 120 ohm terminating resistor.
Where the DMX is feeding through to other modules further down the cable, this link should be removed.