Problem coverting a 5V analog signal to a 20 V digital signal (suggestions?) 3

[clay1551]

Hi,

I am looking for something to convert a 5V analog signal to a 20V digital signal. I am not sure if an I/O board or a A/D board is the best option, or perhaps something different. Does anyone have any suggestions or recommendations for a particular board or solution for this problem? Also, I am hoping to have the output 20V signal to be a minimum of 12 bits. Thank you!

 

[IRstuff]

Why would you need 20V digital? Are you talking about some sort of serial interface?

TTFN
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[clay1551]

It is for a highly specialized digital system. I am just looking for a piece of equipment or a solution method to convert a 5V analog signal to a 20V digital signal.

 

[OperaHouse]

I'm sure that doesn't make sense to anyone here. is the input a linear voltage that varies anywhere form zero to 5V and trips at some voltage threshold, then creating a 20V signal or is it a pulsed signal representing a voltage. Everything we do here is specialized.

 

[ScottyUK]

Standard A/D with a driver array to provide level shifting for the A/D output, e.g. one of the ULN series chips perhaps? How fast is the the A/D operating?

 

[VEBill]

"I am just looking for a piece of equipment or a solution method to convert a 5V analog signal to a 20V digital signal."

Not meaning to be too critical here, but the word "just" implies that you've provided a complete description of a trival problem that requires only a quick part number answer. These manifold assumptions are most likely untrue.

Scotty might be on the right track, but we will only be sure if you more fully described the details.

Analog input signal: 0 to +5v?
Digital output: 12-bit resolution. Parallel? Serial? Format?
20 volt: huh? Weird! Source? Sink? Load? How much current?
Speed? Update rate? Requirement for clocking?
Etc.

 

[DRWeig]

I'll add one more to VE1BLL's list: By 'digital' do you mean binary (on/off)?

Best to you,

Goober Dave

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[clay1551]

I have attached a visual schematic of the current set-up. Our ultimate goal is to be able to read force values from the load cell into our computer. In order to do that, we must have a 20 V digital [binary (on/off)] signal going into the adept controller's JDIO3 port (Part No. 30350-10352). The load cell is a JR3 100M40A. The transformer is our power supply for the load cell. The transformer is providing the 5V analog signal to an A/D board (1 input) and we are converting it to a 5V digital signal (8 outputs). The A/D board is a NI USB-6009 (

http://sine.ni.com/nips/cds/view/p/lang/en/nid/201987)

and the total current coming out of the A/D board is 68 mA (8.5 mA per output). We then used an operational amplifier to boost the voltage from each 5V digital outputted from the A/D board to 15V digital (here is where the problem with this set-up is, because we need 20V digital). The operational amplifier that we used was an LM324N (which can only boost our voltage from 5V to 15V). The operational amplifier circuit was done on a Global Specialties PB-10 (

http://www.alliedelec.com/search/productdetail.aspx?sku=70156527).

The problem with this set-up is that we would ideally like to purchase one piece of equipment that could do all of this work for us (perhaps with LabVIEW or some other software). We feel that this will cause us to experience a delay when taking force readings from the JR3 load cell, if we can ever create a 20V digital input to the Adept Controller.

- I have talked with the local Adept distributer near where we are located, and he suggested a TTL Booster(Transitor-Transistor-Logic) in order to boost the digital signal.
- Also, I have contacted National Instruments, and they directed me to NI CompactDAQ devices (which would eliminate the A/D Board and Operational Amplifier from the current set-up).

I apologize if any of this is still unclear. Please feel free to ask me to clarify anything, if any important information has still not been answered. Also, an alternate solution method suggestion would work for us as well. Thank you all very much for your help.

 

[IRstuff]

Don't see schematic. Is this the controller?

http://www.auctiva.com/hostedimages...,669115859,669115886&formats=0,0,0,0&format=0

What's marked JDIO3 appears to be an output.

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[clay1551]

Yes, that is the controller. I apologize it might not be the JDIO3. It is the JDIO input. Sorry for the confusion, I am just a summer intern!

 

[analogkid2digitalman]

Why not use just one of the digital outputs on the USB-6009 to fire a transistor, mosfet, or optomos that has a 20V pullup?

-AK2DM

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"It's the questions that drive us"
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[IRstuff]

Do you have the actual owner's manual for this thing? There's an obviously marked RS-232 port, which would seem to make infinitely more sense to interface to.

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[VEBill]

"Our ultimate goal is to be able to read force values from the load cell into our computer. In order to do that, we must have a 20 V digital [binary (on/off)] signal going into the adept controller's JDIO3 port..."

I Googled "JDIO3" and the 400-page Adept manual popped right up as the top hit.

If this Adept controller has any flexibility, a different input might be better than forcing a single data word into a row of discrete input I/O pins.

A consideration you might not have considered is that you would have to latch your data word so that the bits are not changing as the Adept scans across the bits. Hint - that's why nobody would ever do it this way.

According to Table 5-5. DIO Input Circuit Specifications (page 112/402), the threshold is about 8 volts. A garden variety single ended OpAmp would be able to provide this input.

Don't forget to latch the data and consider how you'll avoid timing problems if the transitions are not synchronized with the reading cycle.

I'd find a way to interface it using a more suitable port. The basic problem is you've decided to use an unsuitable port.

Good luck.

 

[analogkid2digitalman]

"Our ultimate goal is to be able to read force values from the load cell into our computer. In order to do that, we must have a 20 V digital [binary (on/off)] signal going into the adept controller's JDIO3 port..."

I must be missing something here- if the above is the goal, then all you need is the load cell, its conditioing electronics and the PC/USB-6009.

If you are insisting on taking the load cell value sampled by the 14 bit 6009, then decimating it 8 bits to send it to the Adept then your resolution is going to be pretty coarse (not sure what 5V full scale on the load cell represents).

Also, the digital ouputs on the 6009 are not hardware timed, they are at the mercy of your loop rate and subject to jitter and delay from the OS. Estimating ~750 Hz max rate.

-AK2DM

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
"It's the questions that drive us"
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

 

[MacGyverS2000]

Done plenty of V+ programming for Adept controllers... are you sure the digital version of the signal you care about is not already available from the controller? V+ is slow as sin, but unless you need real speed, the data is likely awaiting you to pluck it from a variable...

Dan - Owner

http://www.Hi-TecDesigns.com

 

[Madcow]

Check the voltage output of the LM324 board. It looks like the JDIO should accept anything over 10vdc as a high. Chech the circuit because the LM324 can run upto 32 vdc in single supply. You may have to just tweek some values on that circuit.