Hello all, first-time poster here.
First off, I am so happy with the Duet! It's a well-designed and thought out board, with a good user interface via DWC and documentation that is an order of magnitude better than most of what is out there. So thank you for making and supporting such an excellent product.
I am trying to use a Duet 2 Wifi to control a cartesian printer, and running into an issue controlling an external stepper driver. Details about the setup as follows:
Firmware Name: RepRapFirmware for Duet 2 WiFi/Ethernet
Firmware Electronics: Duet WiFi 1.02 or later
Firmware Version: 2.02(RTOS) (2018-12-24b1)
WiFi Server Version: 1.23
Web Interface Version: 1.22.6
The printer itself is a Flashforge Creator Pro, which I am in the process of converting over to a clay-extruding printer. In practice, this means I removed the original plastic extruder heads and the original motherboard (mightyboard 1.4) from the FFCP, but left all the axis motion components untouched. I replaced the mightyboard with a Duet 2 wifi, and the plastic extruder heads with two new extruders, one smaller "screw" extruder that runs on 400mN.m stepper, and a larger "ram" extruder that runs on a 1200mN.m stepper attached to a worm drive reduction mechanism. The ram stepper is too large for the Duet's onboard drivers, so I am controlling that with a DM542S external stepper driver, which is in turn controlled by the "conn_lcd" connector (channel 10). I am not currently able to get that external driver to receive a proper input from the Duet 2 and send an output to the ram stepper. The PSU is 24VDC.
I've attached my config.g file, a datasheet for the DM542S, and a couple photos of the setup to this post, and below are the voltage readings I am getting across various terminals when I try to manually run the motor with the "extrude/retract" buttons in DWC.
Wiring between the Duet 2 conn_lcd connector & the DM542S
(1) +3.3V --> ENA+
(2) GND --> DIR- & PUL- (in parallel, I got two wires into a single crimp on the Duet connector end)
(5) EN 10 --> ENA-
(7) DIR 10 --> DIR+
(9) STP 10 --> PUL+
When I turn everything on, I measure on the external stepper driver:
2.75 VDC across EN-/EN+
2.7 VDC across DIR-/DIR+
0.016 VDC across STP-/STP+
When I send a movement command to the motor via DWC, I measure:
2.75 VDC across EN-/EN+ (no change)
2.7 VDC across DIR-/DIR+ (no change)
0.054 VDC across STP-/STP+ (small but consistent rise in voltage. As best I can tell from a digital multimeter readout, this is either a square wave or a nice steady sinusoid, it ramps up and then back down very smoothly)
Unsurprisingly, that small mV pulse to the STP terminals does not seem to trigger the external driver. All the output terminals remain static during movement commands. I don't believe anything in my config.g file should be explicitly causing the low signal voltage, but am not strongly confident about that.
I am fairly sure that the wiring itself is okay, since the larger stepper motor is definitely getting passed some current (it heats up very slightly when turned on, and heats up more when it is commanded to move via DWC). I did crimp all the wires into a plastic connector (to interface with the conn_lcd port), so it's possible that I have some contact resistance or a bad connection on one or two of the wires? That way lies madness though - I figured I'd check here on the forum to see if I was doing something obviously boneheaded before I start really mistrusting all my physical connections and verifying them with wire-by-wire ohm readings.
If there's any other information I can provide or tests/troubleshooting steps that would be useful, please don't hesitate to let me know and I will try them out & report back ASAP.
Thank you!
Eric
config_inprogress.g
DM542S.pdf