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Capacitec non-contact measuring probe plus DRC optical encoder





I work at a jet engine overhaul facilty and we use some very out-dated DOS software to measure the gap between our rotor blade tips and the shroud that surrounds it.


 The setup consists of:

1) a DRC/MicroE systems Model S15 incremental optical rotary encoder that is used to measure the angle location of the measurement probe.

2) a Capacitec non-contact displacement probe that is attached to the rotor blade to measure the gap without contacting the shroud.

3) a Capacitec amplifier model 4100-SC-LG for which the probe connects to.


All of the information from the setup is currently run into a computer that is configured with DOS and then translated by a Capacitec owned software.


My Question:


I would like to get Labview to be the software that could do this measure by connecting it to the Capacitec amplifier and the DRC encoder? (It seems very possible I just need to know where to start.)




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Message 1 of 8

Hi Drew,


We would love to help you integrate LabVIEW into your solution.  Do you already have LabVIEW?  Also, what is the connection mechanism to the PC for the encoder, etc.?  You may consider going to to talk to someone to buy LabVIEW.  When you buy LabVIEW, you receive a 1 year service subscription, which entitles you to email and phone support for our products.  Please let us know. 

Stephen Meserve
National Instruments
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Message 2 of 8



Yes our facility has just purchased the license for Labview. I have been going thru the tutorials from the Labview Evaluation DVD. I imagine someone on site has the email/phone contacts for the service subscription, but they have not told me who yet.


The encoder is connected to the PC via a serial port (RS-232/DE-9, except it's backwards,the male end is on the cord).


The capacitive probe is connected to the amplifier which is in turn connected to the PC via an Industry-standard 37-pin D-Sub connector. it only utilizes the #19 pin (black wire) & #37 pin (red wire). Also #4 & #6 pins are connected and #5 & #24 pins are connected. The amplifier also has to be grounded to the shroud via an alligator clip. So the non-contact prode is reading a voltage I believe.


Thanks Again - Drew

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Message 3 of 8

Hi Drew,


It sounds like you are using serial communication.  You can find examples in the LabVIEW example finder if you select Help»Find Examples... and search for serial.

Stephen Meserve
National Instruments
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Message 4 of 8

Ok I currently trying to get the encoder to commincate via the serial port. I am trying the Instrument I/O Assistant in order to begin the communcation with the encoder. Is this the correct path? If so I am getting a bunch of error codes.


Thanks Again

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Message 5 of 8

The Instrument I/O assistant is the Express VI way of getting started with serial communication.   It can do the job.


What error codes are you getting?

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Message 6 of 8

Ok I just had a 1 hour class session with an applications engineer and I believe I want to use the DAQ assisstant to at least acquire a signal from the encoder.


But I can't seem to find the correct function.


This is from an engineer from DRC:

"The DRC encoder model S15 is an incremental encoder. It will generate digital pulses as the glass disc rotates. As these are simply incremental pulses and not a unique data word as you would get with an absolute encoder, there are no “data bits” or “stop bits”, etc."

So I know its generating digital pulses, which means within the DAQ assisstant I should select: Acquire Signal --> Digital Input --> ???. Or should I try to use: Acquire Signal --> Counter Input--> ??. All the options I try result in "No supported devices found".

What should I try next.


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Message 7 of 8

Hi Drew,


You cannot use a DAQ Assistant to read information from a serial device.  You will need to use the Instrument I/O Assistant as Ravens Fan mentioned.  Have you been able to find any documentation on what type of signal you should be expecting from the device?  It does not sound like a typical serial device, so you may have some difficulty using it in this way.

Stephen Meserve
National Instruments
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Message 8 of 8