Vetting Clearpath S14972 Schematic

[CigarClimatology]

The title says it all. Has anyone actually tried this for functionality?

Clearpath says this:

AND...

the Clearpath S14885 schematic (the old one) appears to do just that. However when the spindle runs, my servos fault!

The new schematic (appears) to isolate the coil circuit from current, dependent on a sinking connection to energize the relay coil. I cannot get the relays to close as HLFB+- do not short when the servo is energized!

Any ideas, am I doing this wrong, or bad data?

I am going to run standard (coil) IDEC 12DVC relays that I have in place here, run 12VDC through the circuit and see if it works. Any additional thoughts would be appreciated.

I am curious if anyone has gotten this circuit to work as proposed.

Thanks

[Richards]

I am not using the relay board shown in the example, so my results will not match what the diagram is showing. On my ClearPath motors, I have the HLFB (+) lines each tied to +24VDC. The HLFB (-) lines are tied to individual PLC input lines, as per the ClearPath documentation. The PLC sorts out the logic, sending a single OK signal when none of the drives have faulted and a FAULT signal when any or all of the drives fault. (Polarity is configurable in the Wizard and in the PLC logic.)

It seems to me that the HLFB (+) signal should be connected to +5VDC and that the HLFB(-) signal would be connected to the coil on the relay block. I'm assuming that the relay block expects a sinking signal to activate a coil. Because the Teknic ClearPath motor has no internal voltage driving the HLFB signal, it requires an outside circuit to provide power.

[Gary Campbell]

A few notes, as there are always more than one way to skin a cat.

First, I would not connect the HLFB output in any configuration directly to a relay coil. One because of the "flyback" voltage release of an un snubbed coil and secondly because the ClearPath specs clearlt state that that output is NOT for inductive loads, which a coil surely is. That said, if you use an Acorn relay, or the $4 eBay versions I have posted on a few times, they are a powered relay module, with opto isolation, so all you are driving with the HLFB circuit is an opto.

The connection as I make them are HLFB- (red) to neg common and HLFB+ (grn) to the relay input terminal. For the most part, I set my relay modules jumpered for "low" signal. These are NC circuits, so the relay is active (on) normally, and opens when the servo is "NOT READY" My relay modules use 24vdc for board power and the Acorn versions use 5vdc. No difference as the Clearpath, even if using this a signal high switch is comfortable anywhere between 5 and 24vdc, (like MikeR mentions) with 24vdc being preferred by the Teknic support agents I speak with.

Remember that you will not get HLFB signal thru the clearpath until it is powered up, enable is active and unit is ready to run

[Richards]

Gary is correct about not connecting the HLFB lines directly to a relay coil. Coil inductance creates serious over voltage problems unless you also use a fly back diode. Even with a fly back diode, the coil current may be too high for the limited current available from the HLFB. That's why I use a PLC.

I don't know how the relay block sold by Centroid works (whether the coils are driven directly or whether they're driven by an on board opto-coupler and whether a fly back diode is already incorporated or whether the user needs to add one).

Unfortunately, as good as the ClearPath motors are, whoever at Teknic it was who said the HLFB signals could be daisy-chained (as shown in the pre-version 4 schematics) must have been using motors different from mine.

The v.4 schematic from Centroid has all of the needed elements to get a reliable signal from each ClearPath motor and then to combine all of the signals by "and get" the relay outputs. That logic is exactly how the ladder logic diagram inside my PLC handles things. When things don't work as expected, I hook up a scope and look at the signals. Not only will a scope verify that the signal is working, but it will show there is voltage overshoot because of the absence of a fly back diode. The trace will also show if the circuit is drawing more current than the HLFB circuit can produce. (Someday I'll breakdown and buy the new relay board or just buy a new version Acorn so that I can add the new relay board to my test bench.)

[cnckeith]

Thanks for posting Mike,
I'm hoping Arturo at cnc4pc will consider making a clearpath motor cable connector adapter board to Acorn screw terminal with a built-in facility to take care of the clearpath enable signal at the same time. This would be pretty sweet to have a plug-in play board for clear path to acorn.
Maybe a few emails from clear path users to Arturo would push him over the edge

[CigarClimatology]

I am not using the relay board shown in the example, so my results will not match what the diagram is showing. On my ClearPath motors, I have the HLFB (+) lines each tied to +24VDC. The HLFB (-) lines are tied to individual PLC input lines, as per the ClearPath documentation. The PLC sorts out the logic, sending a single OK signal when none of the drives have faulted and a FAULT signal when any or all of the drives fault. (Polarity is configurable in the Wizard and in the PLC logic.)

It seems to me that the HLFB (+) signal should be connected to +5VDC and that the HLFB(-) signal would be connected to the coil on the relay block. I'm assuming that the relay block expects a sinking signal to activate a coil. Because the Teknic ClearPath motor has no internal voltage driving the HLFB signal, it requires an outside circuit to provide power.

This appears to be the way to go, as you actually got it to work. While not completely in the dark, my 'primary' world is not the PLC world.

When you mention PLC, are you talking Acorn's PLC or a stand alone? I never thought about adding one, but I suppose I can if that is what it takes to make this thing work!

If you have any sort of schematic to show how you inevitably wired your system, I would love to see it. I was under the impression that these schematics were tried and tested but I suppose not. While the new drawing might work in theory, it does not work. The Clearpath servo needs to be enabled prior to the HL circuit closing. That being the case, my Acorn requires a command for movement prior to enabling the servo. Once enabled the relays to close, not fast enough however to stop the fault that follows movement and an open DriveOk circuit.

I am still getting familiar with Acorn. Can ladder logic be written for this board by the owner?

Ultimately I was hoping for a bit more plug and play and not needing to become a CNC guru to get this to work. This was one of the shortfalls of K2s system in the first place! It did not work as promised. Frankly, I did not want another 'project.' I wanted my CNC to work after following a schematic. I thought I could build this to a schematic and get back to making parts and money with my machine.

Thanks to all those that have pitched in and helped.

-Ray

[Centroid_Tech2]

The Centroid supplied relay board is a 5vdc optocoupled board. The current required to operate the optocouplers is well within the Clearpath HLFB specifications. I have this layout wired on the test bench right now and it's working fine.

[CigarClimatology]

The Centroid supplied relay board is a 5vdc optocoupled board. The current required to operate the optocouplers is well within the Clearpath HLFB specifications. I have this layout wired on the test bench right now and it's working fine.

... you have this working with actual Clearpath SDSK servos, or are you simulating them? How do you get them to assert without enabling them?

[Richards]

Here's a simple circuit that I'm using right now to test the ClearPath HLFB signal on my test bench. The 4N25 Opto-Coupler separates the ClearPath signal from the output signal. Then on the output side of the 4N25, the LED turns on when the ClearPath's HLFB line is active LOW, meaning that the ClearPath servo is able to move. As a side note, the enable signal to the ClearPath motor is not active until the Acorn board turns it on. In my case, as soon as I press the F3 key to start MDI, the enable signal goes active and then stays active. Also, if I load a file, the signal goes active when the file starts to run. The enable MUST be active before the ClearPath HLFB signal goes active LOW. (On my test bench, I have the enable signals to all of the servo motors controlled by a PLC so that I can control when the enable signals become active and so I can control the conditions under which the signal stays active.)

ClearPath HLFB test circuit

ClearPath_HLFB.JPG (30.86 KiB) Viewed 3920 times

[Centroid_Tech2]

The Centroid supplied relay board is a 5vdc optocoupled board. The current required to operate the optocouplers is well within the Clearpath HLFB specifications. I have this layout wired on the test bench right now and it's working fine.

... you have this working with actual Clearpath SDSK servos, or are you simulating them? How do you get them to assert without enabling them?

I have a Clearpath SDSK motor wired up on my test bench and when I jog that axis or enter MDI the relay is activated.