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Old September 15th, 2011, 11:17 AM   #1
ALIMARY15
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PLC DL05 with encoder signals wiring

Good evening,
I am working on a project where i am using a plc DL05 with an encoder to control an axis position.

My encoder signals A and B, i connected them to the input X0 and X1 of the plc because i am planning to use the HSIO MODE 40 for the quadrature encoder as it states into the plc data-sheet.

I have read that this plc doesn't support signals below the 12 V while instead my signals from the encoder are in TTL logic that means 0-5 V.
As anyone of you ever encountered this problem??how you did solve it??

In my case, to make the signal level fine for the plc i have used a IC circuit called ULN2803. This component i connect one pin to the 5 v and the other one to the 12 V power by a pull-up resistor and to the plc as in the scheme showed attached. When from the right pin side there is a signal, the opposite side pin shows zero and viceversa. So in my case when there is 5v to the other side there will be 0v and if i wanna calculate the Pull-up value that will be Rpul= (12V-0v)/max current into plc.

THe component works just fine and it shows to me the quadrature encoder signals between 12V and 0. Now my question is how can i make the plc be aware of the inputs?
It may seem stupid but i am in need in calculating the pull up resistor value in order to make a certain value of current to arrive to the Xo and X1 inputs.
I don't know what is the current value to make the plc read my signals? I have tried to use a current of around 3mA and calculate the pull up value with this current but the plc doesn't seem to read the inputs.

Thanks a lot

Maria
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Old September 15th, 2011, 11:28 AM   #2
icky812
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According to the manual the input needs >5ma to be true. The manual can be found here.
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Old September 15th, 2011, 11:40 AM   #3
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to solve your problem you could use this: H0-CTRIO I think. it is under $200
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Old September 15th, 2011, 12:23 PM   #4
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A 600 ohm pull up should give the 5 ma at 12 VDC.
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Old September 15th, 2011, 01:05 PM   #5
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Bernie have you been down that road before? it sound like you may have been there.

I know the math works out as well.
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Old September 15th, 2011, 01:14 PM   #6
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Also, 1/4 watt would be on the edge (12 volts across the 600 ohms). Better to use at least 1/2 watt resistors as pull-up.
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Old September 16th, 2011, 03:06 AM   #7
ALIMARY15
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Quote:
Originally Posted by bce123 View Post
to solve your problem you could use this: H0-CTRIO I think. it is under $200
Thanks I have also the h0-ctrio but we wanted to try to simply use the dl05 module without programming the ctrio module
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Old September 16th, 2011, 03:07 AM   #8
ALIMARY15
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Quote:
Originally Posted by bernie_carlton View Post
Also, 1/4 watt would be on the edge (12 volts across the 600 ohms). Better to use at least 1/2 watt resistors as pull-up.
Thank you so much! Im gonna try with 600 Ohm resistance. Do you think that also a 1.2 K will work?
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Old September 16th, 2011, 06:54 AM   #9
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600 ohms provides 5 ma into the input impedance as listed for the module. Of course you can try anything you want but 600 ohms is the result of the calculation. Two 1.2 K in parallel would also work.
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