4
PULSE LENGTHS
When the pulse length parameters show a data value from 1 to 250 then only a MIDI ON message is
required as the output will turn itself off again after the specified time. If they show ‘oFF’ then the
outputs will remain on until an OFF message is received. The time shown is approximate in
milliseconds.
INPUT & OUTPUT CONNECTIONS
Connections for the GP Inputs are on the lower pair of 9 pin D connectors. Below is the view looking at
the back of the unit and is the same view as looking at the solder connections of the corresponding
plug.
Pins 1 – 8 are the input pins and pin 9 is the common ground connection. The input pins are internally
pulled up by 4K7 ohm pullups to +3.3 volts. Shorting an input to ground (pin 9) activates that input.
Connections for the GP Outputs are on the upper pair of 9 pin D connectors. Below is the view looking
at the back of the unit and is the same view as looking at the solder connections of the corresponding
socket.
Pins 1 – 8 are the output pins and pin 9 is the common connection. Pin 9 can be + or – relative to pins
1 to 8. The GPOs can switch up to 50 Volts at 100mA of resistive load. If you are switching inductive
loads (such as conventional relays) ensure you use a snubber circuit or you will damage the solid state
relays inside the
GPMX-16
.
MIDI analyser mode:
The
GPMX-16
has a built-in MIDI analyser function. This feature allows you to see what types of MIDI
messages are being transmitted by your master keyboard/sequencer making the
GPMX-16
a useful
diagnostic tool.
To enter analyser mode, you must power on the
GPMX-16
whilst holding the
SELECT
button. The
display will then show ‘rC’ for receive channel & status mode. This means the display will show the
MIDI receive channel of any messages it receives in the right hand two digits, and will show status in
the left digit – this is explained further down the page.
Using the
INC
,
DEC
, and
SELECT
buttons, different types of MIDI messages received may be
displayed:
SELECT
Short press
[rC] Receive channel & status
Long press
[PC] Program change
DEC
Short press
[nt] Note number
Long press
[nv] Velocity
INC
Short press
[Cn] Controller number
Long press
[Cv] Controller value
For whichever of the above selected, the
GPMX-16
will display the value it receives for the type of
message currently selected.
