I have a DMC-4123 and I am attempting to wire in limit switches (Forward and Reverse). I also have Galil 2M, 44 pin cable # 89140-0644 with the pin out information.
My problem is that I am unsure how to wire the limit switch. In my (limited) experience a digital switch has power coming into the switch and a negative. In a normally open configuration, when the switch is activated, current flows back to the cpu and turns the digital input True.
My problem is this: The pin out information has one pin i.e. #7 for the home switch "A". The manual highly recommends a separate power supply for the inputs (which i have), so I am quite confused on exactly how to wire the limit switch.
I am not an electrical guy by any stretch of the imagination so any plain english directions you might be able to give me would be greatly appreciated.
AndrewS on
07/21/2017 - 08:41
Hi tangentem1,
With TTL, the controller's CPU reads voltage as high or low (5V or 0V). In programming, this give a 1 or 0. Since voltage is a potential difference, this voltage reading is always with respect to digital ground.
Now, for opto-circuits, really, we're looking for an internal LED to be on or off. To turn on an LED - there needs to be current flow through it. We use bi-directional optos, meaning that the direction of current doesn't matter - it just a matter of if there's current or not.
To get current, we need to apply a potential difference between two points of at least 5V, but no greater than 24V. The two points are LSCOM and the limit switch.
For simplicity, a typical digital switch has 3 pins - Power pins (Vs and a Reference) and the signal. The signal's voltage reading will toggle between these two power pins. This means we need to connect one of the power pins to LSCOM, and the signal pin to the limit switch input. If we connect the Reference to LSCOM and the signal pin is at the same voltage state as Vs, then the LED will be on. Similarly, if Vs is connected to LSCOM, and the signal pin is at the same voltage state as Reference, then the LED will be on.
Now I would recommend taking a look at the schematics in the DMC-41x3 to get a more complete understanding of this. Keep in mind that LSCOM is shared between all the limits and homes - so you'll want to make sure that you are consistent with all the sensors that you use.
EricK on 03/07/2001 - 16:10
Valis on 03/08/2001 - 09:45
BarbaraW on 03/12/2001 - 10:57
tangentem1 on 07/20/2017 - 08:04
I have a DMC-4123 and I am attempting to wire in limit switches (Forward and Reverse). I also have Galil 2M, 44 pin cable # 89140-0644 with the pin out information.
My problem is that I am unsure how to wire the limit switch. In my (limited) experience a digital switch has power coming into the switch and a negative. In a normally open configuration, when the switch is activated, current flows back to the cpu and turns the digital input True.
My problem is this: The pin out information has one pin i.e. #7 for the home switch "A". The manual highly recommends a separate power supply for the inputs (which i have), so I am quite confused on exactly how to wire the limit switch.
I am not an electrical guy by any stretch of the imagination so any plain english directions you might be able to give me would be greatly appreciated.
AndrewS on 07/21/2017 - 08:41
Hi tangentem1,
With TTL, the controller's CPU reads voltage as high or low (5V or 0V). In programming, this give a 1 or 0. Since voltage is a potential difference, this voltage reading is always with respect to digital ground.
Now, for opto-circuits, really, we're looking for an internal LED to be on or off. To turn on an LED - there needs to be current flow through it. We use bi-directional optos, meaning that the direction of current doesn't matter - it just a matter of if there's current or not.
To get current, we need to apply a potential difference between two points of at least 5V, but no greater than 24V. The two points are LSCOM and the limit switch.
For simplicity, a typical digital switch has 3 pins - Power pins (Vs and a Reference) and the signal. The signal's voltage reading will toggle between these two power pins. This means we need to connect one of the power pins to LSCOM, and the signal pin to the limit switch input. If we connect the Reference to LSCOM and the signal pin is at the same voltage state as Vs, then the LED will be on. Similarly, if Vs is connected to LSCOM, and the signal pin is at the same voltage state as Reference, then the LED will be on.
Now I would recommend taking a look at the schematics in the DMC-41x3 to get a more complete understanding of this. Keep in mind that LSCOM is shared between all the limits and homes - so you'll want to make sure that you are consistent with all the sensors that you use.
Regards,
Andrew