Creating wiki page "Duet wiring"

I created the page "Duet wiring" on the wiki here: [reprap.org]

I have not reused the T3P3 doc as polarity were missing and I have not the source.
Source files (Libre office draw) are supplied, which may help for other schematic. [reprap.org]

I added SSR wiring for Bed and Chamber heater and also controlled fan supplied in 5V. The diode forward voltage is ~0.4V.

Note that my D-Box is wired as on the second schematic (except I only have one controlled fan).

Edited 3 time(s). Last edit at 04/28/2016 06:52PM by PRZ.

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Pierre

- Safety [reprap.org]
- Embedded help system for Duet and RepRap Firmware [forums.reprap.org]
- Enclosed delta printers Lily [rouzeau.net] and Lily Big [rouzeau.net]
- OpenScad delta printer simulator [github.com]
- 3D printing on my site [www.rouzeau.net]

Hi Pierrre,

Firstly thanks for the wiki page it will be handy when my board finally arrives.

Now onto a couple of comments and questions. (you may not have all the answers)

- the Bed connector, shouldn't that be Vout as it provides voltage to the bed?
- same comment on the E H0/1 connectors as these drive the heaters hence Vout.
- same for the fan outputs.

- Vin, just what is the Vmax number? Is the board 30v tolerant? I ask as most common voltage regulators (linear or switch mode) that may be used are often 36v Max rated.
- why "bang-bang", isn't it normal PWM? I use PWM all the time with DC-AC SSRs.

Cheers
Phil

Hi Phil,
I use Vin to qualify the voltage against 5V or 3.3V, and this is what is used in the schematics (in fact this is actually V_IN), including all connectors. I have seen on others boards symbol Vmot, but Duet use only one voltage for all power. It may be possible to invent a symbol like Vb for Board voltage, but that may be troublesome for people looking at the schematics.

The problem of the Duet is there is not much spec. Either you shall dive in the board design or read a few thousand forum messages. I have read in the forum that the maximum was 30V, but I don't know if it is the ultimate voltage or if it is usable at this voltage.

Bang-bang does not do PWM, just on/off to limit the switching heat on SSR. If you have high inertia on the bed (which is more or less normal), it overshoot significantly. Others firmware are doing PID regulation with a very low PWM frequency (0.2-0.5 Hz).

I just get that thread here: [forums.reprap.org], which tells that the frequency was modified recently to 10Hz for Bed and chamber, so that may be ok with SSR. I may switch my bed to have a look how it does work.

In principle the Firmware know the E1 is used for chamber heating as it is defined by M141 (H0 is the bed, H1 is E0, H2 is E1, see M563) . However, there is a problem of timeout on Extruder heaters, as it is unique for all extruder heaters, so unsufficient for a chamber.

Edited 3 time(s). Last edit at 04/28/2016 10:13PM by PRZ.

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Pierre

- Safety [reprap.org]
- Embedded help system for Duet and RepRap Firmware [forums.reprap.org]
- Enclosed delta printers Lily [rouzeau.net] and Lily Big [rouzeau.net]
- OpenScad delta printer simulator [github.com]
- 3D printing on my site [www.rouzeau.net]

Hi Pierre,

I have done DC lighting controller designs as a hobby in recent years so I guess i'll pour over the board design and specified parts to see what is possible unless DC42 chimes in with a number, Dave has mentioned 30V to me in another thread though.

I get that Vin is the label used in the circuit design but it's typical to label the board something like Gnd and +V on outputs, not worth a big debate though, it is just confusing if your coming from outside the community

Cheers

The absolute maximum input voltage for the Duet is 35V, which is the rating of the aluminium electrolytic capacitors on the board. I regard 30V as a reasonable maximum for the planned input voltage when designing a printer.

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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].

Thanks Dave, saved me installing k-cad again, (never liked it for doing pcb design). Guess i'll just re purpose one of the 27V 350W SMPS units i have lying around and run it around 30V
Cheers

Quote
PRZ
In principle the Firmware know the E1 is used for chamber heating as it is defined by M141 (H0 is the bed, H1 is E0, H2 is E1, see M563) . However, there is a problem of timeout on Extruder heaters, as it is unique for all extruder heaters, so unsufficient for a chamber.

I'll change my next release to not apply the timeout to the chamber heater, just as it isn't applied to the bed heater.

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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].

Thanks David.
I got miscellaneous troubles with my chamber heating (most are my fault), but I definitely think enclosed printers are needed for miscellaneous reasons.
Though, the temperature control may not be that easy. Up to bed 100°C, positive heating is required, however at higher temp (110/130°C - real bed surface temp) and after may be half an hour, you may need to extract heat (edit: over ~60°C chamber temp). There is a second fan control available on the Duet 0.8.5, so this is feasible.

That is with a printer which dissipate a lot of heat. I will go from my very boxy form factor to the Lily form factor, which will be fairly less dissipative, meaning that you may have to extract heat while printing ABS. What may be possible is to make macro selecting positive heat while printing PLA/PETG or pre-heating the chamber, then switch to controlled extraction control or better, use the bed as a pre-heater, removing the need of a chamber heater.
I will have to add a check valve for extraction, as my chamber is fairly tight.

I tested PID control on the bed, no problem and no heating of the SSR, but with 1.2A on a 25A SSR (280W on 230V), I have some margin...
You see the SSR led flickering.
This swap to PID control was also needed as I installed recently a printbite surface, which have a significant insulating effect on the bed, which was quite troublesome for the bang-bang control. I found reasonably stable parameters with overshoot not exceeding 3°C (I had more than 10°C overshoot with bang/bang control).

Edited 1 time(s). Last edit at 04/29/2016 12:32PM by PRZ.

---

Pierre

- Safety [reprap.org]
- Embedded help system for Duet and RepRap Firmware [forums.reprap.org]
- Enclosed delta printers Lily [rouzeau.net] and Lily Big [rouzeau.net]
- OpenScad delta printer simulator [github.com]
- 3D printing on my site [www.rouzeau.net]

Quote
PRZ
Thanks David.
I got miscellaneous troubles with my chamber heating (most are my fault), but I definitely think enclosed printers are needed for miscellaneous reasons.
Though, the temperature control may not be that easy. Up to 100°C, positive heating is required, however at higher temp (110/130°C - real surface temp) and after may be half an hour, you may need to extract heat. There is a second fan control available on the Duet 0.8.5, so this is feasible.

You can configure fans on the Duet to be thermostatic. So why not configure one of them to be thermostatic based on the chamber temperature? The only downside I see is that you will have to configure the fan thermostat temperature at the same time as setting the chamber temperature. But you could set up macros to do this for the chamber temperatures you commonly use.

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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].