Program Joystick in logic ladder

[CharlesX]

I need to write a LADDER program in STEP7 that will interface an APEM industrial joystick (js9000). The supply voltage is 15V max.
The joystick has to control a two-axis linear electric drive.
i.e if the joystick is held in the up direction, the x-axis drive moves up
if it is held in the down direction, the x axis drive moves down, etc.
I attached the spec sheet for the joystick. I also added a connection diagram. I only have to do the interface of the analogue joystick.


Can anyone show me how to start this program
I'm a novice.
C

 

[Bobbias]

Well, your going to be going into an analog card. That means that before you start telling the motors what to do, you need to scale the inputs.

Fro what I understand, the way the joystick works is that each axis's center position is at %50 of the voltage, and it goes from 0 to full voltage, 0 being "down" and full voltage being "up".

So you'll need to basically figure out how fast you want "full speed" for each of the motors to be. Once you have that, you'll scale the raw analog card input to that value, so that full voltage represents full speed in the "up" direction, and 0v represents full speed in the "down" direction for each motor.

 

[CharlesX]

Hi Bobbias
OK, I have scaled the inputs and set full speed to 1150 rpm. All the hardware configuration has been completed. My only problem nw is writing the code or constructing the ladder logic circuit

 

[Lay95]

Hi CharlesX,
I am facing same problem. My problem is writing the code or constructing the ladder logic in PLC and also how to scale (set it maximum voltage for forward direction and minimum voltage for reverse direction) it in the ladder logic.
Can you please help me with any solution.

 

[VAN]

Lay95 you look like you are 10 years to late to the party, might start a new thread asking for help.

First I would look for how to scale and that should basically take care of your problem.

 

[Lay95]

Hi Van, I thought that, I might be too late for this conversation. But I appreciate for your help. Thank you.
Here, how to scale means, just to figure out that it will work on 4-20mA and at what range of voltage (0-10V) and lets say 5V will be rest condition.

 

[VAN]

Look up "how to scale in RSLogix 5000" and get a link like: http://www.plctalk.net/qanda/showthread.php?t=22504

Personally, I make my own scaling functions so I can add to it as I need.

Once you have scaling figured out the rest of your question should be just about solved.

 

[L D[AR2P#0.0]]

Hi CharlesX,
I am facing same problem. My problem is writing the code or constructing the ladder logic in PLC and also how to scale (set it maximum voltage for forward direction and minimum voltage for reverse direction) it in the ladder logic.
Can you please help me with any solution.

What platform are you working with?

 

[Lay95]

Thanks Van.
I will look into it.

 

[Lay95]

Hi LD,
My controller is micro820 and I am thinking to use 800T-T2F3DDXX AB 2-WAY JOYSTICK but not yet finalized.
Joystick is used to move bar pusher (it is used in power generator house) forward and backward.

 

[Peter Nachtwey]

I normally suggest that the joysticks analog signals are directly connected to the controller to avoid scan delays caused by the relaying data through the PLC. The PLC can still read the analog data from the controller.


The way I read the data is that if the joystick power is 10 volts then the output is 0 to 10 volts with 5 volts being neutral. 10 volts is full speed in the positive direction and 0 is full speed in the negative direction. What happens if the power is turned off to the joystick? The motors will travel full speed in the negative direction.


So here is the story. In Anaheim CA there is a Disney Land with a dragon that is used in a Fantasia show. In this case there was a show controller that was sending analog signals to the motion controllers in a similar way there 0 volts was full negative of retract motion.


Some one turned the power off to the show controller so the motion controllers saw 0 volts and every one of the 5 articulated actuators in Murphy ( the dragon ) retracted at once a full speed. When the actuators reached the end of travel the inertia ripped Murphy from his bas. Obviously there there was a little damage to Murphy. The show couldn't go on for a while
http://www.disneyphotoblography.com/2012/08/murphy-dragon.html
The motion controllers were doing what they were told to do. They obeyed the 0 analog signals they got.

The simple solution was to remove power from everything at once but then the dragon would slow droop but at least it didn't slam into the ground and rip it off its base.


Be careful

 

[VAN]

I normally suggest that the joysticks analog signals are directly connected to the controller to avoid scan delays caused by the relaying data through the PLC. The PLC can still read the analog data from the controller.


The way I read the data is that if the joystick power is 10 volts then the output is 0 to 10 volts with 5 volts being neutral. 10 volts is full speed in the positive direction and 0 is full speed in the negative direction. What happens if the power is turned off to the joystick? The motors will travel full speed in the negative direction.


So here is the story. In Anaheim CA there is a Disney Land with a dragon that is used in a Fantasia show. In this case there was a show controller that was sending analog signals to the motion controllers in a similar way there 0 volts was full negative of retract motion.


Some one turned the power off to the show controller so the motion controllers saw 0 volts and every one of the 5 articulated actuators in Murphy ( the dragon ) retracted at once a full speed. When the actuators reached the end of travel the inertia ripped Murphy from his bas. Obviously there there was a little damage to Murphy. The show couldn't go on for a while
http://www.disneyphotoblography.com/2012/08/murphy-dragon.html
The motion controllers were doing what they were told to do. They obeyed the 0 analog signals they got.

The simple solution was to remove power from everything at once but then the dragon would slow droop but at least it didn't slam into the ground and rip it off its base.


Be careful

I feel like the limits should have been known and as they approached the motion controller should have been "smart" enough to max dec.

edit - only talking about Disney.

 

[Lay95]

Thanks Peter and Van.
I will try to implement it and will let you know.
Thanks.

 

[Peter Nachtwey]

I feel like the limits should have been known and as they approached the motion controller should have been "smart" enough to max dec.

edit - only talking about Disney.

How would limiting the max dec help.
The controller control output could be limited to +/-5 volts or +/- 1 volt to limit speed but I know limiting the control output to +/- 1 volt would limit normal function.

The motion controller could have been programmed to limit the control output but if the set point to a PID changes by a large amount, the control output will saturate.

The motion controller cannot read minds that are intentionally left blank.

 

[VAN]

How would limiting the max dec help.
The controller control output could be limited to +/-5 volts or +/- 1 volt to limit speed but I know limiting the control output to +/- 1 volt would limit normal function.

The motion controller could have been programmed to limit the control output but if the set point to a PID changes by a large amount, the control output will saturate.

The motion controller cannot read minds that are intentionally left blank.

I guess I'm not thinking of having the motion controller being the brains. I'm thinking PLC to motion and the PLC has position knowledge and when you hit a limit/distance your max speed drops and the PLC is the brains that stops the motion. I don't think I would ever hook controls directly to a motion controller, that just seems like a bad idea.