Convert rs422 to 4-20 mA

[Kenny Bechard]

Forewarning: I have very little electrical and/or signal knowledge so I apologize if this is an elementary question.

I am shopping around for an industrial linear position device and I've come across one that fits my needs physically. However, it outputs a rs422 (or 10...30V) and I want a 4-20mA signal. Is there an easy way to convert that? Is there a recommended standard # for an analog 4-20mA signal (As I said, I'm TOTALLY new to this signal/controls game)? Also, I know that there may be some resolution loss but I have some leeway there because the position sensor outputs at 10x the resolution I need. Thanks.

 

[FvM]

RS-422 is a digital interface standard (and it's voltage range isn't 10..30V). https://en.wikipedia.org/wiki/Rs422

So the signal has to be converted back to analog with a DAC. I presume there will be other devices with analog output.

 

[Kenny Bechard]

Yes, there are other analog devices. So, I prefer converting the RS-422 to analog versus changing the way I receive.(well, not me, that's what the controls guy fed me) Do I have options? Are there standard DAC's for this or do I need to know any special info.

For "10...30V" above, it seems that the product spec one line said RS-422 or 10....30V and in another referenced RS-422, 10...30V (HTL). Another dumb question: so, what is the 10...30V (HTL) refer to. I googled HTL=High Threshold Logic but should that concern me?

Note on my main purpose and as to why I have no knowledge on this: There are some available transducer-type/LVDT-type linear measurement device with 4-20mA output .....BUT for ranges of 75"-120" they are very expensive so I'm shopping for alternatives withing the scope of the linear current (4-20mA).

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Yes, there are other analog devices. So, I prefer converting the RS-422 to analog versus changing the way I receive.(well, not me, that's what the controls guy fed me) Do I have options? Are there standard DAC's for this or do I need to know any special info.

For "10...30V" above, it seems that the product spec one line said RS-422 or 10....30V and in another referenced RS-422, 10...30V (HTL). Another dumb question: so, what is the 10...30V (HTL) refer to. I googled HTL=High Threshold Logic but should that concern me?

Note on my main purpose and as to why I have no knowledge on this: There are some available transducer-type/LVDT-type linear measurement device with 4-20mA output .....BUT for ranges of 75"-120" they are very expensive so I'm shopping for alternatives withing the scope of the linear current (4-20mA).

 

[FvM]

Are there standard DAC's for this or do I need to know any special info.

I'm not aware of standards DAC devices with serial input. They need to be programmed/configured for the specific protocol of the position sensor, so "standard" is a bit difficult.