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i am trying to figure out how to wire up a limit/homing switches to my break out board (stb4100) the one i have has one connection for all homing and one connection for limits my question is does anyone have a pic of how to hook this up i have a induction proximity switch npn type with a power supply of 24 volts dc.
I found this diagram online
Attachment 426874
the solution to your question depends on details like the part number of your proximity switch
the LJ12A3-4-Z-BX proximity switches for example have a 10K pull up resistor built in
that can cause problems when the switch is powered by a 24V supply and you are connecting it to a 5V logic circuit
you may be able to parallel several proximity switches and
connect the the black out wire to the stb4100 input and blue switch negative to the stb4100 input commom
going by a photo of the stb4100 I have made a guess of the possible inputs and
would add the diode shown on my diagram to stop the
stb4100 input from going over +5V if you are using a proximity switch with a built in pull up resistor
Attachment 426876
if you measure the open circuit voltage between the -V terminal used as the switch common and an input
and the input opto-isolator input is powered by a 5V supply you should see 4 to 5V across the terminals and you should find 5V at the vias
(plated through holes ) in this photo taken from the manual
Attachment 426878
if its +24V at the vias the resistors limiting the LED current will be about 1500 to 2200 ohms
john
i am using urbest 8mm detecting distance sensor inductive proximity switch npn no dc 6-36v i am using a power supply of 24v dc i tested out tonight put the resistor on the hot lead (brown) to the input lead (black) the resistance was 22k ohms and it fried it up then i tried to hook up the resistor inline with the input lead (black) to the break out board side it dropped the voltage down only 1.3 volts my question is can i just use a 3 or 4 ohm resistor inline to get volt drop to 5v or will that not be sufficient and would eventually burn up also? will a diode stop this from happening . i also see the opto-isolator you included would that be enough to send a 5 volt signal without having to hook the resistors and diodes? i guess that takes place of soldering all the separate components into one board correct>
I need more details of the proximity sensor than "urbest " and can't see how you burnt a 22k resistor with a 24V DC supply
(current with resistor connected to 24V = 24/22000 = 0.00109 A
power dissipated 0.00109 x 24 = 0.026W )
can you measure the open circuit voltage between a stb4100 input terminal and the switch common V-
Attachment 426898
assuming your NPN proximity sensor uses the same wire colour coding as a LJ12A3_4_Z_BX
can you measure the voltage between the black output wire and blue negative supply when the brown supply wire is connected to +24V
whats the voltage when your proximity switch is on and when its off ?
LJ12A3_4_Z_BX internal circuit
Attachment 426900
John
the power supply is 24v but the readable output is 22.3v it was a 22ku ohm resistor but i neglected to have a diode between the brown 24v to the black input lead the measured reading at the time before it burnt up was 21.6 v without being flagged it dropped down to .620v when flagged, i ordered last night the opto-isolator 24v to 5v will hook up the black lead to high side of isolator after going thur it will deliver 5v to input side that should do it? i see your schematic and see the diodes before the 10k ohm resistor to black wire and the the 2ohm resistor to input side of breakout board the opto-isolator looks like the diagram you have posted with the resists and diodes, with the same placements of both resistor and diodes only $7.00 per board figure i only need two input one for limits and one for homing. so hopefully this should remedy this issue
I am not convinced the 22K resistor is the correct value - 22000 ohms ( red red orange gold ? )
what colours are the coloured bands around the resistor ?
Did you measure the open circuit voltage between a stb4100 input terminal and the switch common V- ?
if so what voltage did you measure ? (see first diagran in post 4 )
with the proximity switch only connected to the 24V DC supply
if your switch has an open collector output like this
Attachment 426920
the output should be 0V when its on and when its off
the only time you should see the output at +24V is when a pullup resistor is connected between the output and the positive supply
either like the 10K resistor inside the LJ12A3-4-Z-BX as shown in post 4
or when you have an external pull up resistor
thats why I need to know the part number to find the proximity switch data sheet
knowing what the open circuit voltage between a stb4100 input terminal and the switch common V- is
will determine how you can connect the proximity switch to the stb4100
if the open circuit stb4100 voltage is +5V and the proximity switch output switches between 0V and +24V
you can not connect the proximity switch output directly to the stb4100 input without further investigation !!!!
you can only connect the proximity switch output directly to the stb4100 if
1) the open circuit stb4100 voltage is +5V and the proximity switch output both on and off is 0V
or
2) the open circuit stb4100 voltage is 24V and the proximity switch output switches between 0V and +24V
John
PS
just read post 6
once I have the answers I will have a closer look at which version of the opto isolator board you need
the part number is LJ18A3-8-Z/BX
also the resistor colors were brown three black lines and then a brown line
so the proximity switch is a LJ18A3-8-Z/BX and has an internal 10K pull up resistor
the brown three black lines and then a brown lines decodes as 100 ohm 1%
when connected across the +24V supply and the proximity switch output
when the switch is on the current through the resistor will be
24/100 = 0.24A
power dissipated = 0.24 x 24 = 5.76 W !
so any 1/2 or 1 W resistor will burn
you do not need to add any pull up resistor
the last piece of the puzzle
what's the open circuit voltage between a stb4100 input terminal and the switch common V-
Attachment 426990
John
While waiting for the voltage measurement between the stb4100 input terminal and the switch common V-
and if possible the current when an input is connected to the V- via your multi meter set to the 200 mA range
I have been looking at the resistor values found on a 24V to 5V opto-isolator board
and been speculating on the values to expect on a 24V to 24V board
as I have not found one up to now
Attachment 427026
John
sorry john i was measuring the input and the brown leads off the proximity sensor wasn't getting what you wanted, the voltage off the breakout board from the neg lead on the board and input pin on board is 20.6 now does mean it can handle the 22 volt current or do i still need a resistor to lower voltage?
i thank you for your patience and understanding you obviously gathered i know little to nothing about electronics
That will indicate the stb4100 input terminal is connected to the +24V via a resistor and the LED inside the opti-isolator as in the last photo in post 2
most of the missing 2V will be the forward volt drop across the LED
That means you can connect the proximity sensor directly to the stb4100 input terminal
when the proximity sensor switches on the NPN transistor will ground the stb4100 input terminal to the -24V supply
and I would expect a current of about 10mA will flow out of the stb4100 input terminal and to ground via the proximity sensor
you can check this by connecting a stb4100 input terminal to ground via a meter set to the 200mA range
John
so i was worried about burning up the board for no reason i can connect it to the breakout board directly without doing any harm and don't need to drop voltage any the board with handle the voltage ?
yes, this time
with other breakout boards or motion controllers designed to work at 5V logic levels it could of been different
without any detailed information thats why I wanted to know what the stb4100 input open circuit voltage was
now we know both the stb4100 input circuit and the proximity sensor both work at 24V levels
you can connect them together
John
thanks you john for your understanding and patience i do appreciate the help and information
thank you
as long as you have your machine working
this is what you should have when the proximity sensor is connected to a stb4100 input
Attachment 427040
without your measurements I could not be sure there was not a voltage regulator reducing the +24V to a lower voltage to power the opto-isolators
John
i have another question i hooked up the proximity sensor and its 20.6 and it drops down to .62 when its flagged but my question is on the breakout board it says there should be 0-10v at the dac and common part do you think it needs to be hooked up to the vfd to initiate the volt flow ? it also hook to the start and stop for the spindle?
Once mach3 is setup and sending a PWM signal to the DAC (digital to analogue converter)
you should see the 0 to 10V control voltage between the DAC and COM terminals
Attachment 427076
I have not found a high resolution photos to reverse engineer the board to be sure the COM and -V terminals are isolated or connected together
but from this photo you can see the +V connection goes via a diode that prevents damage if the 24V supply connections are reversed
( the diode can be seen in the bottom left hand corner )
In general board follows the design pattern followed by many breakout boards
Having what I expect to be a ULN2801 transistor array in a socket is a great advantage
the IC can easily replaced if you short circuit the +24V to one of the 4 outputs
A week ago I replaced a damaged FET in a AXBB motion controller
see posts 39 & 40
AXBB charge pump fault - Page 4
John