No Input Signals
22 Oct 2015 00:30 #64089
by andypugh
Yes, but, you should be able to power it with 24V and have it switch a 5V input pin between 5V and 0V.
This is _exactly_ how my lathe limit switches work, so I know it is possible. (although I am connecting to a Mesa card)
Replied by andypugh on topic No Input Signals
I can't use the proximity switches with 5V. I tested it and they start working at 12V. When I apply 5V a) the led won't light up and b) it won't switch from 5V to 0
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Yes, but, you should be able to power it with 24V and have it switch a 5V input pin between 5V and 0V.
This is _exactly_ how my lathe limit switches work, so I know it is possible. (although I am connecting to a Mesa card)
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22 Oct 2015 00:33 #64090
by alfongs
Replied by alfongs on topic No Input Signals
but how do I realize this? I only got one extra wire which I can measure to gnd :/
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22 Oct 2015 00:49 #64093
by andypugh
What voltage are the pull-up resistors connected to?
If you connect the sensor black wire to one end of a resistor and the other end of the resistor to 5V then you should see the black wire switch between 5V and 0V.
If the inputs on the BoB are varying between 0V and 24V then _something_ is funny about your pull-up arrangement.
Replied by andypugh on topic No Input Signals
but how do I realize this? I only got one extra wire which I can measure to gnd :/
What voltage are the pull-up resistors connected to?
If you connect the sensor black wire to one end of a resistor and the other end of the resistor to 5V then you should see the black wire switch between 5V and 0V.
If the inputs on the BoB are varying between 0V and 24V then _something_ is funny about your pull-up arrangement.
The following user(s) said Thank You: alfongs
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22 Oct 2015 01:04 #64096
by alfongs
Replied by alfongs on topic No Input Signals
The pull-ups are connected to +5V and directly soldered to one leg of the optocouplers (on BOB).
I'm further looking into this tomorrow to get a switch between +5v and 0 at the screw terminals.
But I'm also preparing to get a new bob in case my 24V have burned the optocouplers ...
I'm further looking into this tomorrow to get a switch between +5v and 0 at the screw terminals.
But I'm also preparing to get a new bob in case my 24V have burned the optocouplers ...
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22 Oct 2015 01:29 #64099
by PCW
Replied by PCW on topic No Input Signals
If you added the resistors shown in the picture, that wont help as those are on the wrong side of the OPTOS (the parallel port side)
That patch was done to make the BOB work with a specific motherboard and is not what you need to do
If you really have NPN proximity switches they _CANNOT_ output +24V unless you have an unconnected ground or they are wired incorrectly
NPN proximity switches would need a pullup resistor at the BOB input terminal (the Screw terminal which is in the input side of the OPTO isolator)
That patch was done to make the BOB work with a specific motherboard and is not what you need to do
If you really have NPN proximity switches they _CANNOT_ output +24V unless you have an unconnected ground or they are wired incorrectly
NPN proximity switches would need a pullup resistor at the BOB input terminal (the Screw terminal which is in the input side of the OPTO isolator)
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22 Oct 2015 02:42 - 22 Oct 2015 02:43 #64105
by cncbasher
Replied by cncbasher on topic No Input Signals
the 12 - 14 volts input is for power only not for the pins of the parallelport
you want no more than 5v on a parallel port pin .
it's ok to supply 12 to 24v to proximity switches , this does not give , as you may think 12 -24 volts on the output pin
they are logic out , i.e like a transistor not a switch .
if you want to protect the input from any damage , place a 200 - 300 ohm resistor in series with the input pin
then use a 1 or 2k resistor from the bob side of the 200 -300 ohm resistor and connect that to no more than 5v from the bob
( theirs a regulator on board to bring the voltage down to 5v) you need the pull up resistor to 5v because your using npn proximity
but the chance is the bob is already lifting the pin to 5v , because of the opto , so you may not need it .
i have used similar breakout boards , and have not had to fit any pullup resistors or series resistors , and they have ran fine for years .
although the series resistors will help reduce any damage.
you want no more than 5v on a parallel port pin .
it's ok to supply 12 to 24v to proximity switches , this does not give , as you may think 12 -24 volts on the output pin
they are logic out , i.e like a transistor not a switch .
if you want to protect the input from any damage , place a 200 - 300 ohm resistor in series with the input pin
then use a 1 or 2k resistor from the bob side of the 200 -300 ohm resistor and connect that to no more than 5v from the bob
( theirs a regulator on board to bring the voltage down to 5v) you need the pull up resistor to 5v because your using npn proximity
but the chance is the bob is already lifting the pin to 5v , because of the opto , so you may not need it .
i have used similar breakout boards , and have not had to fit any pullup resistors or series resistors , and they have ran fine for years .
although the series resistors will help reduce any damage.
Last edit: 22 Oct 2015 02:43 by cncbasher.
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