need help wiring 4 clearpath motors

[Richards]

After reading the ClearPath Manual, Appendix D (where it lists the specs on HLFB as being suitable for non-inductive loads with 9mA maximum current draw), I ran a few tests to see how much current the coils of the relays I have on hand draw. The Omron from Grainger draws 39mA. The TK73-624 that I saw on Marty's YouTube video for OUTPUT use draws 17mA. The TLP1A-F624-N that I bought by mistake from the same supplier, draws 10mA. I didn't have any other 24VDC relays on hand. All of those relays are inductive loads and all draw more than the maximum current specified by Teknic, although experience tells me that probably all would work.

Next, I prototyped a simple three transistor layout. The bottom two transistors (2N2222) would connect to a ClearPath motor's RED data wire with the ClearPath motor's GREEN wire connected to +24VDC, making the HLFB a SOURCING circuit. That means that if the motor is working normally, it would output 24VDC on the RED wire. With the RED wire ON, the transistor turns on. The bottom two transistors would each be connected to a Clearpath motor's RED wire. The top transistor is connected to Input-5 on the ACORN. If ON transistor is ON, then its collector is at ~ 0VDC and its LED is ON. If both of the bottom transistors are ON, then the top transistor's base input would be OFF. If the top transistor is OFF, then its collector is not conducting and the connection to Input-5 on the ACORN floats HIGH (In MillWizard, Input-5 is DriveOK, N/O). If both bottom transistor are emulating a DriveOK HIGH signal, then the ALT-I screen would show a green light for Input-5. If EITHER of the bottom transistors is OFF, then the top transistor connected to Input-5 conducts, and Input-5 shows a red light.

Here are some photos that show what I've written about. Excuse the mess and the disorganized state of the test setup.

[Richards]

Here's a schematic for the prototype circuit in the photos of my last post. Because my ClearPath SDSK motors have not yet arrived and because I exchanged the original motors for those that are in transit, I'm doing everything from memory and everyone knows that you can't trust the memory of a senior citizen. If I find that this circuit does not work when the motors arrive towards the end of next week, I'll post a schematic that does work. The resistors are all 1/2 watt. The values on the schematic worked for my prototype test.

The HLFB signal is NOT self-powered. Read your ClearPath manual carefully (pages 41-50 and Appendix D) and look at the diagram that they have for a SOURCING circuit.

The 10K resistor between the ClearPath signal and the transistor limits the current to about 2.5mA.

Of course, I can't assume any responsibility for how you use this schematic. If you decide to try it out, FIRST make a prototype without connecting it to the ACORN or to the motors. For preliminary testing, connect the Anode side of LED 5 to 24VDC. Connect the Anode side of LEDs 1-4 to +24VDC. LED 5 should be OFF and LEDs 1-4 should be ON. Then, one at a time, disconnect LEDs 1-4 from +24VDC. That LED should turn OFF and LED 5 should turn ON. Use your multimeter's current setting to verify that LEDs 1-4 are pulling less than 5mA each when they are on. Use your multimeter's current setting to verify that LED5 pulls less than 5mA when on. If your prototype passes that test, then proceed with caution. Don't forget to change Input 5 to NO in the Wizard.

[ammercado21]

Another note on the Clearpaths that you may or may not see - pairing the two in software did not work for me. Keith and I have discussed this in the past and it appears to only show up with Clearpaths. The two motors did not move smoothly together. My resolution even before talking to Keith about it was to hard-wire the two motors together at the Acorn terminal block and that solved it.

Hi agsweeney1972,

I am really intrigued by what you did on your clearpaths, if its not too much trouble, can you please explain further what you mean by "hard-wiring" the two motors in Acorn? Is it correct to say that with the hard-wired motors, you only used 3 out of 4 sets of the step/direction pins of Acorn?

Ariel

[Richards]

After thinking about the schematic that I posted, I decided to add one more stage so that Input 5 could be setup as NC. If it is NC, then it could detect a broken wire or open connection which would warn you that repairs were needed.

It's frustrating to make a prototype without having motors to verify the design. I don't know how Teknic handles the HLBF signal when the motor is not ready. My circuit assumes that the RED wire only supplies voltage when the motor is ready and that the RED wire basically becomes an open circuit when the motor is not ready. I'll know what the motor does when my motors arrive.

One more note: If you have fewer than 4 motors, then you would need to connect the input line to the corresponding transistor to +24 volts, otherwise, that transistor would be off, giving a false error signal. I'll only have two motors to work with, so I'll face that problem myself.

In this revised schmatic, Transistor 5 is always OFF unless one of the motors sends an error signal. Because it is OFF, the transistor is not conducting and +24VDC is fed into the base of Transistor 6, which turns Transistor 6 on. If Transistor 6 is on, then it SINKS Input 5 (pulls it to GND), and the ACORN board knows that the DriveOK signal is indicating that no error exists.

[Gary Campbell]

A point of clarification for Mike, who for those who do not know him, is one of my CNC mentors, having freely offered help (a LOT of help) to me (and many others) when I started to tinker with this stuff more than a decade ago.

One of the benefits of the "cheapo Chinese" relay modules that I use, and recommend for combining signals like the ClearPath HLFB, is that they are an opto-isolated circuit that requires ~2-4 ma to trigger that is a non-inductive load. You get the advantage of a "combo pack" of relays, add in the opto input, and jumpers to set hi/lo trigger, and you have win, win, win.

The engineer in him, harped on me to read the data sheets and FOLLOW them. Just a note to say I listened, Obewan

[Richards]

Thanks Gary. Now that I know that the ClearPath signal is going through an optocoupler and not to the relay coil itself, I will probably do exactly as you have done. It doesn't make a lot of sense for me to design a board and pay the high costs of getting boards made when a very affordable solution is already available. (I think that you have the roles mixed up. YOU are Obi-Wan Kenobi and I am the student.)