Limit switch on a ZK-SMC 02 controller

Thread Starter

Dells

Joined Sep 21, 2023
17
I have added a stepper motor to my mill X axis but I need to add a limit switch but not sure where to connect the wires to , the controller has a built in driver for the stepper and the limit switch needs to enable I think , I have limit switch setup with a spring loaded rod so what ever way the table is going the limit switch will operate , here is a pdf of the controller
http://attach01.oss-us-west-1.aliyuncs.com/IC/Datasheet/GY20512.pdf
Any help would be much appreciated
Dell
 

Thread Starter

Dells

Joined Sep 21, 2023
17
Hi MisterBill2
Thanks for replying I need a limit switch to stop the X axis crashing at either end of its travel , I can make something to operate the switch from either direction that’s not a problem it’s where to wire it to.
Dell
 

MisterBill2

Joined Jan 23, 2018
18,975
OK, based on the picture of the control buttons connections, the limit switch should have it's NORMALLY CLOSED contacts in series with the stop button. But with that arrangement there will be a problem of moving back away from the end once the limit switch is operated. And that is an interesting manual indeed.
What it looks like is that if the over-travel limit is tripped, the next step would be switch off the power and manually rotate the stepper motor to back off. If that is possible and not so very difficult that might be adequate. But certainly not the first choice approach.
 

Thread Starter

Dells

Joined Sep 21, 2023
17
OK, based on the picture of the control buttons connections, the limit switch should have it's NORMALLY CLOSED contacts in series with the stop button. But with that arrangement there will be a problem of moving back away from the end once the limit switch is operated. And that is an interesting manual indeed.
What it looks like is that if the over-travel limit is tripped, the next step would be switch off the power and manually rotate the stepper motor to back off. If that is possible and not so very difficult that might be adequate. But certainly not the first choice approach.
Thanks so would it be better to use two limit switches would that make any difference ?
I think I can set the controller to send stepper a number of steps then return and the ideal way would be to set a maximum distance each way but then if power was off and when turned back on if the X axis was in a different place the number of steps would be the same so would crash the X Axis.
I could probably manage with your suggestion but is there a better way ?
Dell
 

MisterBill2

Joined Jan 23, 2018
18,975
With some stepper controller there are dedicated limit switch inputs that just halt motion in a direction when they activate. I did not see that in the application for this controller. If there is additional information I have not seen it.
 

MisterBill2

Joined Jan 23, 2018
18,975
It seems that the "enable" line is already in use. That would be the one to use if it were available. So if there is a way it could be utilized that would be a better choice. BUT the STOP scheme will work.
 

MisterBill2

Joined Jan 23, 2018
18,975
So could I switch the enable ?
Dell
It is not clear what the requirements would be as far as what would be required and exactly what the actual function result would be. IN addition, it is not obvious even which way it would be switched.
So that choice requires more information. That is unfortunate. Do you have more information? Is it possible to contact the actual manufacturers of the system to get additional information?
In the meanwhile, breaking the "stop" circuit should provide a way to avoid damage from driving beyond the limits.
 

LesJones

Joined Jan 8, 2017
4,208
One other thing you need to tell us is does your system count steps up and down for positioning information or are you just using it to move the mill axis . If it is keeping track of position then you will need to consider the effect of disabling the output of the driver will have on the counting circuits. Putting the question another way is this a CNC mill or a manual mill with dials on the leadscrews ?

Les.
 

Thread Starter

Dells

Joined Sep 21, 2023
17
It’s a manual mill with leadscrew and a 3 axis dro for position and it’s only on the X axis to traverse both ways because I have problems with my hands and can’t hold and turn a handle for long anymore.
Dell
 

MisterBill2

Joined Jan 23, 2018
18,975
The limit switch function is rather important on a lead-screw driven mill, unless it is one that already includes limits somehow. The circuit in post #7 looks like a single axis setup, which for that just adding the NC limit switch in series with the "STOP" button should be adequate. And simpler. Not quite as convenient, but I am thinking that it will not be tripped during normal operation.
 

Thread Starter

Dells

Joined Sep 21, 2023
17
The limit switch function is rather important on a lead-screw driven mill, unless it is one that already includes limits somehow. The circuit in post #7 looks like a single axis setup, which for that just adding the NC limit switch in series with the "STOP" button should be adequate. And simpler. Not quite as convenient, but I am thinking that it will not be tripped during normal operation.
I think that is what I need to do because as you say it’s not something that will be a regular occurrence it’s just a safety option just in case .
 

LesJones

Joined Jan 8, 2017
4,208
Is my guess correct that you will use your controller set to "work mode F-01->P02" with an external 3 position (Forward off reverse.) switch ? If this is the case you could connect the NC limit switch between the forward and reverse contacts on the switch and the CW and CCW inputs to your controller. The common on the switch would be connected to the GND connection on your controller.
Les.
 

MisterBill2

Joined Jan 23, 2018
18,975
Is my guess correct that you will use your controller set to "work mode F-01->P02" with an external 3 position (Forward off reverse.) switch ? If this is the case you could connect the NC limit switch between the forward and reverse contacts on the switch and the CW and CCW inputs to your controller. The common on the switch would be connected to the GND connection on your controller.
Les.
I have used a milling machine and what I see is that an unplanned reversal of the table motion while the cutter is working could have quite unfortunate results, or at least unsatisfactory results.
 

Thread Starter

Dells

Joined Sep 21, 2023
17
On my small mill I use conventional milling most of the time , I seem to get better results but I do use climb milling sometimes and the tool is always moved off part before traversing the other way.
Les Jones
Not sure what you mean by connecting to forward/ reverse as the controller already has forward & reverse can you explain further please, sorry but this 70 year old head is struggling to understand.
Dell
 

LesJones

Joined Jan 8, 2017
4,208
If you use the forward and reverse push buttons to traverse the table you would have to find a way to break the path to to push buttons to implement limit switches. On the table feed I built for my mill (A seig X3) I use a three position center off toggle switch for direction, a potentiometer for speed and a push button to do a fast traverse without having too change the speed setting. you can use the push buttons in two ways (Depending on how you configure the controller.) One way is you hold you button pressed to cause thr motor to rotate. The other ids apress of the button starts the motor and it rotates until the stop button is pressed.
Can you tell us how you want it to behave ?

Les.
 
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