Duet + Duex switch I/O pin

Hey there,

I would like to control an external valve by using three I/O pins on the DUEX expansion board. The valve expects a binary code.


example:

binary code: 1 0 0

M42 P36 S1 ;PC4 -> HIGH
M42 P18 S0 ;TXD0 -> LOW
M42 P16 S0 ;TXD1 -> LOW

Unfortunately the valve doesn't expect LOW to be GND (0V) but to be disconnected.

Is there a gcode command to disable I/O pins (or to define them as an input pin)?


kind regards!

Can you provide a link to the datasheet for the valve? It may be possible to use diodes connected to the outputs to do what you need.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Hello,

unfortunately the datasheet gives very very little information (no circuit diagramm at all, only a binary table). But in the past I succesfully controlled the valve by taking pin=5V for binary "1" and pin=input for binary "0".

I would like to stick to this method. Maybe I will define my own gcode command to define general I/O pins as an input.