[bmcd]

I just received my KFLOP board and am ready to start on the challenging task of getting it up and running on my K2CNC 3925 router (Gecko 320 DC servo drives). I am not at all experienced at cnc electronics and need help in wiring and set up. I’ve attached a layout of the wiring with the connections I understand, but am not sure how to hook up the emergency stop switch and the 3 axis home switches. Any advice would be greatly appreciated. Thanks!

[bmcd]

One of the wiring connections I couldn't figure out on my K2 was the emergency stop switch and how to integrate it into the KFLOP system. Mike at K2 informed me that their old set up had the e-stop breaking a connection in Mach3, which means I need to figure out a different method when using KMotionCNC. The Gecko 320 manual indicates an e-stop can be initiated at the servo driver by sending the connection from the Error/Reset pin (terminal 5) to ground. So it seems that the e-stop is a separate function from the KFLOP. If anyone has a different or better way of doing this I'd really like to hear about it.

[TomKerekes]

Hi bmcd,

You might read through this recent Thread on our Yahoo Group.

Regards

[bmcd]

Thanks Tom, interesting thread. From what I can get from this is there are a couple of ways to go about wiring an estop. One way would be doing it at the gecko's by sending the Error/Reset terminal to ground. Another would be cutting the power to the motors. This could be at the ac going into the power supply or the 24vdc between the power supply and the servo drives.

In either of the two cases, does a signal have to be sent to KMotioncnc that an estop has occurred, or will it sense this automatically? If a signal has to be sent, how would I do that and would that involve Pin 4 (Reset#) on the JP7 connection?

[TomKerekes]

Hi bmcd,

Systems like yours are completely open loop from KFLOP's perspective. It is impossible for KFLOP to know that you cut power to the motors or disabled the amplifier and that the motors are no longer moving.

So yes you would want to feed the disable signal into a KFLOP input. You can then have a C Program watch loop monitoring the signal and if it goes active send a command to KMotionCNC to EStop. See the ExternalButtons.c example.

The signal would be tied to a KFLOP Input - not KFLOP Reset.

HTH
Regards

[bmcd]

Thanks Tom for the info. From what I've read, it seems the safest way to wire an estop is to have a dual relay break the power to the motors and send a signal to KMotionCNC that an estop has occured via a KFLOP input. The exact method of setting up the monitoring program is something I will address later. Presently I want to order the various parts I need to wire up the system (new control box, ribbon cable, plugs, relay, possibly a breakout board, etc...). Once I have everything in place and basically set up I can then turn my attention to the fine details and software/hardware interface. I'll post when I'm at that stage. Thanks for the help!

[bmcd]

Systems like yours are completely open loop from KFLOP's perspective. It is impossible for KFLOP to know that you cut power to the motors or disabled the amplifier and that the motors are no longer moving.

Tom, is it possible to set up a KFLOP system as a closed loop? If so, would that require additional hardware and/or set up?

[TomKerekes]

Hi bmcd,

Your system is closed loop. But it is closed loop in the drive (Gecko G320) rather than in the controller (KFLOP). KFLOP basically just tells the drive where it should go and it is up to the drive to make it go there and verify it did. I believe the G320s have a fault signal that could be input back to KFLOP so KFLOP could be made aware of a problem. Or the encoder signals could be paralleled back to KFLOP so it could track the position in parallel with the drives - but that makes for somewhat messy wiring.

Alternatively different drive types could be used that allow KFLOP to control the position feedback loop directly. These might be 3rd party analog drives (controlled with KFLOP+Kanalog) or our SnapAmp.

HTH
Regards

[bmcd]

It's been awhile since I posted on this topic as I had to finish a project. I've got almost all the parts needed and mounted in a new case. Just waiting for a capacitor and resistor for the load dump circuit of the e-stop. I'm using a slightly modified version of the one posted on the Gecko website. My question today is regarding the wiring to tell KFLOP/KMotionCNC an estop has occurred. My preexisting estop button has 2 wires connected to the switch. When they are connected together, all is well, when the switch breaks the connection everything stops. I'm assuming a similar set up is used for the KFLOP, if not, what are the differences? An earlier posting mentioned a disable signal would be sent to a KFLOP input with a monitoring program to used to trigger the estop. Is it possible to use one of the inputs on the JP7 for this purpose? At this point I'm only using pins 15-24, so all the rest are available. If I can use my old estop button, is there a suggestion as to where the 2 wires should be connected? Thanks!

[TomKerekes]

Hi bmcd,

It isn't clear what you are intending to do or if you understood the links we posted earlier. There are many ways to handle EStop. It is up to you to assure your system is safe. Usually the drives and/or power are disabled directly by the switch with out any involvement of the controller, software, or any programs or configuration. But then additionally it is often good to inform the controller that EStop has occurred so that the Software stops whatever is going on even though it wouldn't make any difference physically to the machine because it has been already powered down or disabled anyway. Do you understand this?

Regards

[bmcd]

Yes, I understand there are 2 parts to the estop I'm setting up, when all that is really needed is to stop the machine quickly, regardless of the software. My hope is a simultaneous shut down of the software will enable me to keep from losing my home position. Is this possible or just wishful thinking?

My estop button has 2 switches internally and therefore can have a dual function. One cuts power to a relay that shuts down the power supply to the drivers and motors with a load dump cap and resistor to bleed excess current from the filter caps and motors. The other would handle the software side of things. If the home position can't be maintained, I'll have to decide if it's worth stopping the software.

[TomKerekes]

Hi bmcd,

ok I think we are on the same page. But I suspect when the Geckos are disabled the motors may coast some amount and the commanded position will be incorrect regardless of whether the commanded position suddenly stops or not. The best way to be able to recover after a fault or disable is to connect the encoder position back to KFLOP. Doing this will allow KFLOP to properly track the axis position even while the axis is disabled or moved manually. Then when the axes are re-enabled the commanded destination can be set to where the axis actually is based on the encoder position which will eliminate the need to re-home.

Unfortunately connecting the encoder to the drive and KFLOP makes for messy wiring and increases the chance of having noise issues. This is especially true for single ended encoder signals.

Regarding connecting the EStop to KFLOP: KFLOP inputs are 3.3V LVTTL inputs which need to be driven to less than 0.4V as a low signal and greater than 2.8V (but not higher than 3.8v) as a high signal. A simple switch contact will not do this. One solution is to add a pull up resistor (ie 1K Ohms) to 3.3V and then allow the switch to short the signal to DC GND. KFLOP connectors JP4 and JP6 have built in pull down resistors so you might use those and then have the switch short the pin to 3.3V. The EStop signal can be either polarity as a program will be used to test it and the program can check for either polarity.

HTH
Regards

[bmcd]

Hi Tom,

Thanks for the explanation. Since it seems to involve messy wiring and potential noise issues, I think it's prudent for me to pass on trying to maintain my home position after an estop. I'll just use Gecko's power cut off design for the present. Perhaps later I can add the circuit you described if I feel it would be a significant improvement. The last 2 components are due in tomorrow, then full assembly can be completed sometime next week. Then the next step will be installing the software and getting things to communicate properly. At that point I'll cruise the forum and will post again if I can't find the answers needed. Thanks again.
Bob

[bmcd]

Tom,

I have a question just so I'm aware of the capabilities of the KFLOP. If the estop was wired exclusively to the board in the ways you've mention on the forum (no electro-mechanical set up), would that stop the machine via the software and maintain the home position?

Bob

[TomKerekes]

Hi Bob,

I'm assuming you mean to handle EStop entirely as a software input to KFLOP?

First I'd like to make a disclaimer that it is entirely up to you to determine and take the responsibility for the safety of your system.

The problem with handling EStop in software is that any bug in our software, or your software, or your configuration may result in the EStop being non-responsive. This includes somehow running the wrong software, or forgetting to run the software, or loading the wrong configuration. There is also the possibility of a hardware problem, glitch, or noise that might cause the software to execute incorrectly or stop executing resulting in EStop being non-responsive.

But that all being said an EStop input to KFLOP can be monitored and handled in KFLOP however you wish (which is part of the problem). One possibility is to disable all KFLOP Axis channels that will immediately stop all commanded axis trajectories. However such an abrupt stop may well result in a motor drive fault or a motor stall or miss-step which will cause the commanded position to no longer match the actual position. Again if encoders are installed and interfaced to KFLOP, then KFLOP will continue to track the actual position regardless of how the stop occurs. The known actual encoder position can then be used to re-initialize the system to a known position without requiring a re-home operation.

Another option is to have the EStop issue a FeedHold. This should keep all the axes enabled and bring the axes to controlled, properly decelerated stop over some distance. In this case there should be no difference between the commanded and actual positions and no need to re-home. In order for this to work the hardware must all be working properly and there must be room to come to a stop. Obviously this type of EStop would provide no protection in cases such as striking an object or a servo runaway due to loss of encoder feedback.

HTH
Regards

[bmcd]

Thanks Tom for all the information. I've completed all the wiring and am using a slightly modified version of the electro-mechanical estop circuit provided by Gecko. I've run some power up and estop tests on the electronics and everything is working correctly. I've installed the software and now it's time to get the motors talking to KFLOP and configured. I haven't been able to find a step by step procedure on doing this (it would be very helpful), so this is what I've started with.

The machine is a K2Cnc closed loop servo system with Gecko 320DC drives. I've been using Mach 3, but want to use KMotionCNC instead as Mach has been a bit buggy.

I've typed "version" in the console and got a response so the software and board are in communication. From inside KMotion I've opened Configuration with Channel 0 being my x axis. Axis Mode input is set as encoder and I'm assuming output should be set to DC Servo. Examples in help are oriented towards Steppers so that's my best guess. Please correct me if I'm wrong. Not sure what to do with the rest of the settings. I've been looking in the Mach 3 configurations to possibly get some corresponding values, but haven't seen (or recognized) anything at this stage to help. I'm not going to set up the Limit Switches presently, so that's not an immediate issue. I realize that when I've set the options for Channel 0 I should hit "Download Channel" to get the info into KFLOP and do the same for the other 2 Channels (y + z). I've done some looking on the forums but haven't found anything to help as yet. Any advice for the configuration?

By the way, my step and dir connections on the 3 Gecko's are wired into pins 15 through 20 on KFLOP's JP7.

After this is worked out, what's next?

Bob

[Al_The_Man]

There is roughly two ways out there to wire the E-stop circuit, use all the individual recommendations from each supplier of the component parts and then there's the common practice used by the industry for some considerable time and the NEC code and NFPA79, this entails including a hardwired method that includes any O.T. limits Watchdog timer/Charge pump etc.
Which ultimately removes power from motorized devices and usually all output devices, inputs and the controller itself can remain powered.
The controller is also advised of an e-stop via an input.
Al.

[bmcd]

Tom, after a lot of further reading and rereading I've organized my questions for the Configuration Menu in KMotion. First of all as a reminder, I'm setting up a closed loop servo system with Gecko 320DC drives.

The way I have my system wired up on the KFLOP JP7 is as follows:

Pin 15 - IO8 = Axis 0 Step for X axis
16 - IO9 = Axis 0 Dir for X axis
17 - IO10 = Axis 1 Step for Y axis
18 - IO11 = Axis 1 Dir for Y axis
19 - IO12 = Axis 2 Step for Z axis
20 - IO13 = Axis 2 Dir for Z axis

Here are the questions in the Configuration Menu in KMotion:

Axis Modes - Input - Since I'm using these as outputs to the Gecko drives, I'm assuming that Input should be set as No Input.

Axis Modes - Output - Should this be set to Step Dir or DC Servo?

Input Channels - Since I'm using these as outputs only, I'm assuming that Input Channels section can be ignored.

Output Channels - Is the number selected refer to the IO# on the KFLOP? If so, #8 would be selected for my X axis Step going to the Gecko. If that is the case, then where would 9 be set (Dir X axis), as Channel 0 is already configured for 8? Am I a little confused?

Microstepper Amplitude - is this relevant to my system as I'm using servo's?

Max Following Error - As this is for servo setups this applies to my situation. What do the numbers entered refer too? A certain amount of revolution of the encoder or a linear value?

Inv Dist Per Cycle - Not for my system.

Lead Compensation - If I put 0 will there be no compensation?

Once this is completed what is next, the Step Response Menu?

Bob

[TomKerekes]

Hi Bob,

The way I have my system wired up on the KFLOP JP7 is as follows:

Pin 15 - IO8 = Axis 0 Step for X axis
16 - IO9 = Axis 0 Dir for X axis
17 - IO10 = Axis 1 Step for Y axis
18 - IO11 = Axis 1 Dir for Y axis
19 - IO12 = Axis 2 Step for Z axis
20 - IO13 = Axis 2 Dir for Z axis

Here are the questions in the Configuration Menu in KMotion:

Axis Modes - Input - Since I'm using these as outputs to the Gecko drives, I'm assuming that Input should be set as No Input.

Correct

Axis Modes - Output - Should this be set to Step Dir or DC Servo?

Step Dir - this is what your system is from KFLOP's perspective. KFLOP has no idea what the Step/Dir pulses are going to and doing.

Input Channels - Since I'm using these as outputs only, I'm assuming that Input Channels section can be ignored.

Correct. There is no feedback being sent back to KFLOP

Output Channels - Is the number selected refer to the IO# on the KFLOP? If so, #8 would be selected for my X axis Step going to the Gecko. If that is the case, then where would 9 be set (Dir X axis), as Channel 0 is already configured for 8? Am I a little confused?

The Output Channel is NOT the IO#. Rather it specifies which Step/Dir Generator Device to be used and what mode the Step/Dir Generator should operate in. See:
Step and Direction Setup

Microstepper Amplitude - is this relevant to my system as I'm using servo's?

No. it is not relevent

Max Following Error - As this is for servo setups this applies to my situation. What do the numbers entered refer too? A certain amount of revolution of the encoder or a linear value?

No. Again KFLOP has no encoder feedback connection so has no idea of how well the system is following. From KFLOP's perspective the system is open loop. Your drives are closing the loop.

Inv Dist Per Cycle - Not for my system.

Lead Compensation - If I put 0 will there be no compensation?

Once this is completed what is next, the Step Response Menu?

Correct

Regards

[bmcd]

The Output Channel is NOT the IO#. Rather it specifies which Step/Dir Generator Device to be used and what mode the Step/Dir Generator should operate in. See:
Step and Direction Setup

In the Step and Direction Setup link you provided the following is stated:
"If an axis channel is selected as a Step and Direction axis, the corresponding 2 output pins will be automatically configured as outputs"
So this mean IO8 and IO9 will automatically configured as Step and Dir respectively with no independent set up for IO9's Dir function, correct? I believe this is indicated in the KFLOP Table in the Step and Direction Setup link.

As far as the Output Channels Gain setting, in the Output Gain Scripts section of the KFLOP manual it's stated "Normally there is no need to use a value other than -1.0 or +1.0". So I guess I'll leave it at 1.

Max Following Error - As this is for servo setups this applies to my situation. What do the numbers entered refer too? A certain amount of revolution of the encoder or a linear value?

No. Again KFLOP has no encoder feedback connection so has no idea of how well the system is following. From KFLOP's perspective the system is open loop. Your drives are closing the loop.

So does this make it irrelevant? Or should some kind of mystery value be entered (pick a number between 1 and 1,000,000,000)?

Once all this is done I'll repeat it for the Y and Z axis making sure to "Download Channel" for each axis.

Thanks,
Bob