Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: osman100 on April 09, 2009, 08:11:06 AM
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i have a bridge cutter for marble and i tried to modify it as cnc but its axises work by normal ac motor so i choose to drive it with omron f7 inverter with can use it to work as servo but when i use mach 3 i can't change the direction of motor from mach 3 because the driver need a contact between 2 point to change the direction but i don't know the direction signal in mach 3. is it one pulse for every change direction or it's a pulse train or it's a contact so can you help me to know it's uniform and if it possible also how can i convert it to normal contact between 2 physical point by electronic circuit or relay or any other solution all the best
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The Dir signal is a High or Low signal depending on direction. Therefore it should be easy enough for you to do this via a relay, however I think youmay end up with problems as the direction change may well be too slow by this method unless axis speeds are low.
Hood
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thanks a lot hood that's main in on direction it will be hi and in another direction it will be low so i can use a realy but i'd like to ask also about the current on it is enough to make a relay work or may be i'm in need to use a transistor to drive this relay
thanks alot
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Best bet would be to use a powered breakout board I think.
Hood
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i tried to use a relay 5 volt and i connect its coil contact to pin #3 and pin#18 ant take contact from it's contact's but the relay is not work so i think may be the signal from mach 3 is not hi and low o according to the direction can anyone help me to solve this problem
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The signal is High and low, if your PP puts out 5V it will be 5V one way 0V the other, check that pin 18 is grounded properly, also check you have the axis enabled or Mach will not change the dir. Tes with a voltmeter and you will see the Hi/Lo change.
Hood
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about the axis its enable but i'll chick about the ground of pin 18 and tell u thanks a lot
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i checked pin 18 i found its grounded but i also found that when i measure the voltage between pin 3 and pin 18 i found it 3.5 volt and when i conect it to the 5 volt relay it's droped to 1.5 and in the other direction it will be 2.1 milli volt what can i do to solve this problem pls
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I would use a powered breakout board, that will give a true 5v out of the port and should be capable of powering a relay, in fact most have at least one relay on them.
Hood
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can u help me for breakout board circuit diagram drawing
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Afraid not, my knowledge of electronics is lower than zero.
Hood
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dear hood
now my problem was solved there some friend from other site tell me this problem because the current is not enough to drive the load and the volt is 3.5 v at no load but at load it's drop to 1.5 so thy suggest to use switch circuit with transistor according to the following link http://ourworld.compuserve.com/homepages/Bill_Bowden/r_ctrl.htm
i used fig b with transistor 2n222a and now the relay is working probably good
all the best
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Thats great and thanks for the link, I am sure it will come in handy :)
Hood