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Old 11-26-2011, 04:23 PM
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Default MSA LED, MIDI I/O and Programming Questions

C. writes:

I have an MSA-T board I recently soldered together:

1) Do the red LEDs go on and off regardless of an actual load (e.g. relay) being attached to the outputs, or does the load need to be attached?
The LEDs will light whether or not a load is attached.

2) I simply want the MIDI OUT from my computer to turn on and off the outputs. Do I connect the MIDI OUT cable from my computer to the MIDI IN terminals (wire 4 and 5) of the MSA-T or do I connect it to the MIDI OUT terminals of the MSA-T? (If the MIDI IN, don't I need a ground connection, or is this some type of 4-20ma loop only requiring two wires and no ground?)
There are MIDI wiring diagrams in the MSA hardware user manual that should answer these questions.

The correct connection is:

Computer MIDI Out -> MSA MIDI In

...that's all you need to control the MSA-T outputs.

If you want to use Sqwerl for configuration, you should also connect:

MSA MIDI Out -> Computer MIDI In

...this will let Sqwerl "read" the MSA configuration and show it to you on screen.

Yes--MIDI is a current loop system. The "out" or "thru" end of the link has the cable shield connected to ground to prevent interference. At the "in" end of the link, the cable shield is left unconnected to avoid ground loops.

For more reading, straight from the official MIDI spec, see:



Hope this helps.
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Old 11-28-2011, 08:18 PM
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C. writes:

Do I have to program the board using the software? (I thought it simply came preprogrammed to read midi notes and send them to the output based on the dip switch settings.) In other words, don't I just solder on the components, hook up the midi cable and power supplies, and it works or do I need to actually program it first?
The board does indeed come pre-programmed to respond to MIDI notes. The default notes are #s 60-67 (note 60 is Middle C).

If you'd like the board to respond to different note #s and/or to different types of MIDI messages, there are two options:

1. The "learn method" whereby the MSA listens for the notes you send, then remembers them and responds to those notes during normal operation.

2. The sysex method, which is easiest to do using the Sqwerl configuration utiltiy.

The learn method is very easy to do. The procedure is described in the MSA firmware user manual, linked on the MSA doc index. (Page 4 in the version 3.1 manual.)
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