584,833 active members*
5,582 visitors online*
Register for free
Login
IndustryArena Forum > CNC Electronics > CNC Machine Related Electronics > MACH3 AKZ250 BOB WITH NPN NO PROXIMITY SENSORS
Results 1 to 5 of 5
  1. #1
    Join Date
    Dec 2014
    Posts
    35

    MACH3 AKZ250 BOB WITH NPN NO PROXIMITY SENSORS

    Hello Gents

    I have a problem, regarding the wiring of the NPN Normally Open proximity sensors and there seems to be some confusion about this, especially when I refer to the schematic, which the user manual supplies. I will attach two pics of the info, which I have.

    The MACH3 manual shows that the settings, must be set as ACTIVE LOW, when using NPN type proximity sensors.

    The sensors have 3 wires.

    BROWN, BLUE AND BLACK.,

    This is a test, which I did this evening:

    I connected my 24 V DC power supply to the sensor. BROWN wire to BROWN on sensor and BLUE to BLUE wire on sensor. Measured the voltage there and got 24 V. When I placed a screw driver in front of the sensor, the LED came on. This is all Normal.

    A search on YouTube revealed that a resistor was used and attached to the BLACK wire. This wire is the SIGNAL wire and was plugged into the port on the BOB. When the sensor was activated, the voltage dropped to around 0 Volts.

    Further Testing:

    I placed a RESISTOR between the BLUE and BLACK wires and the voltage was shown as 5,8 V with the SENSOR NOT ACTIVATED. When I activated the resistor, the voltage dropped to 0,7 V. This proves the theory of the video clip on YouTube.

    The wiring diagram on the NPN sensor, shows a resistor (load) between the BLACK and BROWN wires. The BLUE wire seems to go to the GND on the BOB (I could be wrong)?

    Please look at the two attached pics and look how the AKZ 250`s user manual, shows the wiring for this BOB?

    If I put a RESISTOR between the BLUE and BROWN wires, I get 23,6 V and when I activate the sensor, the voltage drops to 0,7 V.

    I just want to know the correct way of how to connect these NPN type NORMALLY OPEN sensors to this BOB.

    Regards

    Craig

  2. #2
    Join Date
    Dec 2014
    Posts
    35
    Quote Originally Posted by craig00747 View Post
    Hello Gents

    I have a problem, regarding the wiring of the NPN Normally Open proximity sensors and there seems to be some confusion about this, especially when I refer to the schematic, which the user manual supplies. I will attach two pics of the info, which I have.

    The MACH3 manual shows that the settings, must be set as ACTIVE LOW, when using NPN type proximity sensors.

    The sensors have 3 wires.

    BROWN, BLUE AND BLACK.,

    This is a test, which I did this evening:

    I connected my 24 V DC power supply to the sensor. BROWN wire to BROWN on sensor and BLUE to BLUE wire on sensor. Measured the voltage there and got 24 V. When I placed a screw driver in front of the sensor, the LED came on. This is all Normal.

    A search on YouTube revealed that a resistor was used and attached to the BLACK wire. This wire is the SIGNAL wire and was plugged into the port on the BOB. When the sensor was activated, the voltage dropped to around 0 Volts.

    Further Testing:

    I placed a RESISTOR between the BLUE and BLACK wires and the voltage was shown as 5,8 V with the SENSOR NOT ACTIVATED. When I activated the resistor, the voltage dropped to 0,7 V. This proves the theory of the video clip on YouTube.

    The wiring diagram on the NPN sensor, shows a resistor (load) between the BLACK and BROWN wires. The BLUE wire seems to go to the GND on the BOB (I could be wrong)?

    Please look at the two attached pics and look how the AKZ 250`s user manual, shows the wiring for this BOB?

    If I put a RESISTOR between the BLUE and BROWN wires, I get 23,6 V and when I activate the sensor, the voltage drops to 0,7 V.

    I just want to know the correct way of how to connect these NPN type NORMALLY OPEN sensors to this BOB.

    Regards

    Craig
    The schematic which is in the MACH3 usermanual,shows that the BLUE wire is going to the pin on the BOB. The specifications on the NPN sensor,shows the BLACK wire going to GND (This is if I am correct in saying so?)

    While searching for videos for this BOB,I learned that the BLACK wire is referred to as the SIGNAL wire. This and the MACH3 schematic,look different.

    Regards

    Craig

  3. #3
    Join Date
    Dec 2014
    Posts
    35

    Re: MACH3 AKZ250 BOB WITH NPN NO PROXIMITY SENSORS

    Hello Gents

    I sorted this problem out and its working properly now.

    Regards

    Craig

  4. #4
    Join Date
    Mar 2007
    Posts
    2083

    Re: MACH3 AKZ250 BOB WITH NPN NO PROXIMITY SENSORS

    having had a quick look at the AKZ250 manual

    this is what you have when the sensors NPN open collector output is connected to one of the AKZ250 inputs

    Click image for larger version. 

Name:	no npn sensor plus motion controller.jpg 
Views:	2 
Size:	52.3 KB 
ID:	405656

    I have calculated the additional resistance required to limit the AKZ250 input current to 7mA when you connect it to a +24V supply
    the pull up resistor I calculated is 2700 ohms
    the value given in the manual is 3300 ohms this will reduce the current that will flow into the AKZ250 input
    and will reduce the voltage you will measure at the AKZ250 input terminal to about 4.64V

    when the sensor is triggered and its NPN output transistor short circuits the AKZ250 input to ground
    the voltage at the input terminal will depend on saturation voltage of the NPN transistor -
    the 0.7V you have measured is what I would expect

    as the sensor has a normally open NPN open collector outputs that only sinks current to GND and can not supply current from the 24V supply
    it is safe to connect sensors in parallel
    the AKZ250 will only sense when the first sensor is triggered

    I expect you will need to set the sensor as active low in mach 3
    as the AKZ250 input is high (+5v ) until the sensor is triggered and the AKZ250 input goes low (0.7V)

    John

  5. #5
    Join Date
    Dec 2014
    Posts
    35

    Re: MACH3 AKZ250 BOB WITH NPN NO PROXIMITY SENSORS

    Quote Originally Posted by john-100 View Post
    having had a quick look at the AKZ250 manual

    this is what you have when the sensors NPN open collector output is connected to one of the AKZ250 inputs



    I have calculated the additional resistance required to limit the AKZ250 input current to 7mA when you connect it to a +24V supply
    the pull up resistor I calculated is 2700 ohms
    the value given in the manual is 3300 ohms this will reduce the current that will flow into the AKZ250 input
    and will reduce the voltage you will measure at the AKZ250 input terminal to about 4.64V

    when the sensor is triggered and its NPN output transistor short circuits the AKZ250 input to ground
    the voltage at the input terminal will depend on saturation voltage of the NPN transistor -
    the 0.7V you have measured is what I would expect

    as the sensor has a normally open NPN open collector outputs that only sinks current to GND and can not supply current from the 24V supply
    it is safe to connect sensors in parallel
    the AKZ250 will only sense when the first sensor is triggered

    I expect you will need to set the sensor as active low in mach 3
    as the AKZ250 input is high (+5v ) until the sensor is triggered and the AKZ250 input goes low (0.7V)

    John
    Hello John

    Thank you for your reply.

    I used a resistor on the BLACK signal wire, to the input pin on the AKZ250 and set the sensor to ACTIVE LOW. It was just a little confusing to see how the user manual had shown the wiring of the sensor. I think that this did confuse a few people before?

    Regards

    Craig

Similar Threads

  1. Npn NO proximity sensors
    By Kal22378 in forum CNC Machine Related Electronics
    Replies: 21
    Last Post: 05-18-2018, 05:16 PM
  2. Dual proximity sensors
    By SvenPHX in forum CNC Machine Related Electronics
    Replies: 1
    Last Post: 08-23-2017, 12:47 PM
  3. how many proximity sensors?
    By RobSm in forum CNC Machine Related Electronics
    Replies: 2
    Last Post: 01-18-2017, 09:02 AM
  4. proximity sensors
    By FordGalaxy in forum Benchtop Machines
    Replies: 16
    Last Post: 06-02-2012, 09:36 AM
  5. proximity sensors
    By wired in forum CNC Machine Related Electronics
    Replies: 7
    Last Post: 09-30-2005, 05:29 PM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •