Upgrading a Gorilla CNC from Flashcut to Acorn

[techcreator]

I am presently upgrading a 4' x 8' router CNC from Flashcut to Acorn. The stepper drive on that machine are SilentStep that was made in Canada by a company name Agile System inc (apparently closed now).

My question is very simple; it is possible to have EN1, EN2 & En3 from the BD25 connector on the Acorn?

Since I can find any information on theses drives anywhere on the web, it is impossible to get the input specification voltage for STEP, DIR & EN. I dismantle the case of one drive and luckily, I found the pinout of the input control connector DB9 printed on the PCB. Presently the Flashcut board also use a DB25 with a different pinout configuration then the Acorn but also at TTL Source output voltage to feed these drives input +STEP, +DIR, & +EN with a -STEP, -DIR and -EN wired in a COMMON Ground configuration for all 3 signals.

The STEP and DIR signal are available on the DB25 of the ACORN, but I can find the EN. The EN is available on the Screw Connector and there are many schematics that demonstrate how to connect the EN to the Screw Connector at 5V in a sink configuration. But in my case, I need a Source output not a Sink output. Is any of the auxiliary output signal available on the DB25 was design to be use as EN1, EN2 & EN3?

Regards

[suntravel]

Stepper with ENA from the Headers, Step/Dir from DB25

https://www.centroidcnc.com/dealersuppo ... 032.r2.pdf

Uwe

[techcreator]

Hi Uwe,

Thanks for taking the time to reply, but your proposed solution doesn't answer my need. All schematics supplied by Centroid refer to Sink Output on the screw connectors. In my configuration, STEP, DIR, and EN need to be Source outputs since I am in a COMMON ground configuration. This is true for STEP and DIR when connected to the DB25, as the driver stage on the Acorn board uses an ACT125 3-state Buffer capable of outputting Source or Sink up to 24mA. On the other end, the screw connector uses a Sink configuration with an open collector that allows flexibility of voltage supply, but is almost useless in a Source configuration unless I design a circuit to invert the signal.

Thanks,

Daniel

[Gary Campbell]

If you look on the Schematics page, you will see numerous examples that both source and sink step/direction signals to stepper drives from the DB25 header. FYI... on the advanced page you have the ability to invert signals. No sense over complicating the process, a bit more time in the manual and on the forum should clarify your path.

[centroid467]

Hello Daniel,

You are right that the 74ACT125 tri-state buffers on the DB25 outputs will both sink and source current so wire them as in the DB25 drawings.

I could not find any documentation on your specific drives and I suspect they might be a customized version for Gorilla CNC but from the 7th page of this brochure, I suspect that the Enable wiring in S15032 linked by Uwe will work just fine for you.

Selecting DB25 in the Wizard inverts the enable signal from screw terminals anyway. So, if it does not work try the invert checkbox in the Advanced drive setup page.

Edit:

Wait, common ground as in there is only one terminal each for step, direction, and enable and they all share a single ground pin? If so, give me a few minutes and I'll ask around or come up with a circuit if we do not have any other solution.

[techcreator]

Hi Centroid467,

As I understand from most replies I have received from the community, members do not clearly understand the subtle differences between Sink and Source output with common ground in Source configuration or common supply in Sink configuration.

As an electronic circuit designer, I will then reverse engineer the input section of the drive (SilentStep) to see if I can use it in a Sink configuration with a 5V common on the +(side) without damaging the board. I didn't expect that I would need to probe the circuit with my logic analyzer to solve a low-end issue like the lack of an EN signal on the TTL side of the DB25.

If this works, I will then use the Screw Terminal end with the auxiliary 5V external supply. If the drive has to be common ground, then I will design a simple buffer circuit (pull-up input with a 74ACT124) to get the EN from the Screw Terminal into a Source output.

Nevertheless, I will post my solution later to help anyone who might face this limitation in the future.

Best regards,
Daniel

[tblough]

Most people just resort to adding a relay.

[suntravel]

Yep, I also would use a small SSR, since ENA is not time critical.

Or if the drivers are enabled by default, I would skip connecting ENA, since CNC12 can force home after E-Stop but not if a single drive is disabled.

Uwe

[centroid467]

Hi Centroid467,

As I understand from most replies I have received from the community, members do not clearly understand the subtle differences between Sink and Source output with common ground in Source configuration or common supply in Sink configuration.

As an electronic circuit designer, I will then reverse engineer the input section of the drive (SilentStep) to see if I can use it in a Sink configuration with a 5V common on the +(side) without damaging the board. I didn't expect that I would need to probe the circuit with my logic analyzer to solve a low-end issue like the lack of an EN signal on the TTL side of the DB25.

If this works, I will then use the Screw Terminal end with the auxiliary 5V external supply. If the drive has to be common ground, then I will design a simple buffer circuit (pull-up input with a 74ACT124) to get the EN from the Screw Terminal into a Source output.

Nevertheless, I will post my solution later to help anyone who might face this limitation in the future.

Best regards,
Daniel

Hello Daniel,

Forgive me, I read your initial post too fast and missed some of details of the description.

I don't believe you will need to pull out the LA to figure this one out. If I am reading your description of this right, the common ground connection is on the FlashCut side. I cannot tell from the pictures exactly how it is wired but it looks like there are six wires going to that I/O connector. If there are six wires going to the I/O connector on the drive and you know the pinout (which may match that in the brochure I found) then all you would need to do is determine whether or not the Enable_In-, Pulse_In-, and Direction_In- pins are tied together with any multimeter in resistance or continuity test mode. I would expect them to be separated since they are optically isolated according to that brochure.

If that is not the case then yes, you would likely need to devise some interface circuit. The Acorn's power supply has a nice unused 5V rail that could be of use here.

[techcreator]

Hi Centroid467, many thanks for the excellent technical support. I am very impressed.

I am uncomfortable continuing this conversation, since it now goes beyond typical customer support and you have already exceeded what one would normally expect from a supplier.

--- That said, you are leading in the same direction as I am. Based on the picture attached, the pinout printed on the PCB leads me to think that this drive adheres to the industry standard of +step/-step... and most likely, all inputs are insulated from each other. I did the multimeter test yesterday and they seem to be isolated. But as you can see in the second picture, they installed a bank of reverse protection diodes just across the DB-9, but there is no sign of an optocoupler. I couldn’t identify what those two 8-pin Flat Pack (DIP) 630 821 are on the right of the DB-9 are. They could be dual optocouplers like the VISHAY VO0630T, but I would need to trace the connections to confirm.

I will take baby steps to avoid any damage and hook up one of my floating ground frequency generators to the Step input, and toggle the direction and EN with switches in a 5V sink configuration.

--- You mentioned that you found a brochure. Could you email it to me?

I will keep updating this thread with my findings.

Many thanks for your support.

Daniel