1XD Expansion: PNP vs NPN Control

[p8blr]

On the wiki the single-ended schematic shows a NPN configuration (+ signals held high and - signals switched) and I want to know if a PNP configuration would work as well (- signals grounded and + signals switched) ?

Thank you

[dc42]

@p8blr it would work if you connected the + inputs of the driver to +5V from the 1XD and the - inputs to the corresponding outputs of the 1XD.

However, with your existing wiring there is no need to connect STEP- DIR- and ENA- of the driver to GND unless they are already commoned in the driver. If they are independent of each other then you can connect them to the corresponding outputs of the EXP1XD board instead.

[p8blr]

@dc42 My driver isn't compatible in a differential configuration unfortunately. I would prefer to use the + signals on the 1XD (PNP) if possible.

I'm just wondering how the 1XD works, and if it can be configured as either PNP or NPN signals?

[dc42]

@p8blr if your driver has optically isolated inputs that are compatible with both PNP and NPN style control, then it should also compatible with differential inputs. Please post a link to the driver manual so that I can check this.

[p8blr]

@dc42 Sure. https://teknic.com/files/downloads/clearpath_user_manual.pdf

On page 49, see the "Engineer's Note".

There's a reason I would prefer PNP though, I'm wanting to also use the enable signal to disable a servo brake when the servo becomes enabled.

Thanks.

[dc42]

@p8blr yes you can use the differential outputs from the 1XD with those ClearPathdrivers, because the 1XD provides 5V swing instead of the usual 3V for differential signals. You would not need to use the 1K resistors even if the cables are long.

[p8blr]

@dc42 But, back to my initial question, can I use PNP?

[dc42]

@p8blr your wiring diagram shows that you are already using PNP-style connection.