Clearpath Enable Connections to Acorn

[MarkRH]

I wired mine as per this wiring diagram and the HLFB +GRN wont close the relays the way it is drawn, if IN2 closes that relays it goes nowhere. I had to wire mine on the normally closed side to make it work. Did I read the diagram wrong? wrong relay board?

[Richards]

You're doing fine. You're using NPN sensors. An NPN sensor is OPEN until it senses the target, then it CLOSES. The relay contacts have to be wired so that they are CLOSED so that they can be wired in SERIES; then, when any one of the NPN sensor's sees its target and goes active, the relay that it is connected to open's its contact.

Use the Wizard to change the polarity of the Acorn's Input if necessary (Normally Closed or Normally Open).

[Richards]

Here's a simplified schematic of what happens with NPN proximity sensors when they are connected to relays, with the relays wired in series, with only one input to the Acorn. The function of the proximity sensor is represented by the Sx switches.

On many proximity sensors, the Brown wire is connected to +24VDC, the Blue wire is connected to GND and the Black wire is the signal OUT wire that is connected to the relay coil or directly to an input. On NPN ganged relay boards, +24VDC for all relays are tied together. The device controlling the individual relay is connected to the negative side of the coil.

The schematic shows that when none of the proximity sensors "see" their target, they act like an open switch and the associated relay is Normally OFF. Because the circuit requires a continuous path from the Acorn input to GND, you use the Normally CLOSED connection on the relay. When any of the proximity sensors "sees" its target, its Black wire goes LOW and its associated relay turns ON. When the relay turns ON, its Normally CLOSED connection is opened and the Acorn floats HIGH.

[Gary Campbell]

Whether you connect the homing switches to the Acorn as "All in One" or individually, you can use them with a "gender change relay" setup. Of course, there will be more latency with a mechanical relay than with proper gender changing circuitry, but it should be consistent enough for most home built projects.

[MarkRH]

Mike Richards,
Not sure if you were replying to my post or not, I was talking about the HLFB circuit from a SDSK clearpath motors. As drawn in the diagram it did not work. The alarm circuit opens that common IN5 and causes a fault. My proximity sensors are on IN1 AND IN2.

[Richards]

Hi Mark,
Sorry about that. My brain stopped working years ago when I was in my sixties.

The board that Gary posted will do the job for you.

I've redrawn the schematic to show the "behind the scenes" functionality of my ClearPath HLFB circuits. The switches represent the HLFB circuit inside the ClearPath motors. Page 48 of the Teknic ClearPath manual gives an overview of how the HLFB works. I have my ClearPath motors programed such that Servo ON would pull an Acorn Input LOW. Page 177 of the Teknic ClearPath manual shows the data cable pinouts. The HLFB RED wire connects to GND. The HLFB GREEN wire is connected to the negative side of the relay's DC coil. The positive side of the relays' coils are connected to the same +24VDC power trace on the circuit board. The HLFB signal acts as if it were a CLOSED SPST switch when the servo is ON and the servo has been programmed with Teknic's software to be in the Servo On mode.

Because the HLFB signals are ALL sinking current (LOW) when the servos are ON, the relays will all be active unless a servo faults. The relays must be wired such that the Normally Open contact is wired in series to the Acorn's Input. Because the relays will all be turned ON when the servo is not faulted, the Normally Open contact will be held closed by the HLFB circuit in each ClearPath motor until the motor faults or until power is removed from the motor. (The schematic shows the relays when they are in their inactive state - when they are at rest with the ClearPath motors either powered off or NOT enabled.)

I've personally tested the HLFB circuits on my Acorn Model 3 board using the relay boards recommended by Marty and Gary. That was before CentroidCNC started supplying relay boards with the Model 3 and then later introduced the Model 4 board. I've also used an equivalent circuit with AutomationDirect PLC's. I've wired the HLFB circuits directly to individual Acorn Inputs and to inputs on their 16x16 expansion board. All of the methods worked for me. Using an accessory 4, 6, or 8 gang relay board is the least expensive method if inputs are limited on the Acorn.

[MarkRH]

Mike and Gary,
Thanks for the information, and I dont mean to hijack this thread I didnt start. But reading thru it made me check how I'd wired mine and I tried crashing the Z into a block of wood to fault it and it never did fault this relay board, (wired to NC side to IN5 sees common)



I wired +green HLFB to each of the channels 1,2,3,4, with a supply 5v to DC+ and com to DC -

Applying 5v to any of the 1,2,3,4 channels closes the relay, but it seems the HLFB doesnt supply voltage in a faulted or not faulted state, how does it trigger the relay?

From the Acorn diagram multiple clearpath sdsk I dont see how this works?

I must have the wrong relay board?

Thanks

[Richards]

Mark,
How have you wired the Red wire on the ClearPath data cable? (I'm assuming that you're using the blue factory data cable from Teknic. If not, then isolate the two wires used by the HLFB signal in your cable.)

Some relay boards can be jumpered to use either positive or GND signals to turn on the relay. The ClearPath motor SINKS current. That means that you would use an NPN relay board where you would connect +5VDC to the common (+) terminal on the board. If the relay board can be set to either NPN or PNP, you would jumper the relay board to be NPN. You would connect the Green (+) ClearPath wire to the relay's coil terminal. You would connect the Red (-) ClearPath wire to GND. You would also have to program the ClearPath motor to use Servo ON on the HLFB circuit. With the Servo's HLFB signal set to Servo ON, when the motor is enabled, the HLFB signal allows about 10mA to flow from the Green wire to the Red wire. If one side of the relay's coil is connected to +5VDC, the HLFB (+) wire is connected to the other side of the relay's coil, and the HLFB (-) wire is connected to GND, you will have a complete SINKING circuit. The relay will turn on. When the servo cannot turn its shaft, the HLFB signal will fault, you will have an incomplete circuit, and the relay will open.

Please check the Servo settings in Teknic's MSP software. Is HLFB set to Servo ON? Tell us exactly how you have connected both HLFB wires.

[MarkRH]

Mike
You nailed it, I had the jumpers on high setting thinking the HLFB was a 5v signal, changed the jumpers to Low and the relays closing as they should,
Thanks for your help, much appreciated.