Author Topic: Specific question about an RM Young 26700 Translator and Temp probe hookup  (Read 1909 times)

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Offline DaleReid

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My apologies for what might be a long message.

First, I have a working (many off ebay aren't) RM Young 26700 translator.  It came with a Voltage In board, To that is attached a Young non-tipping (capacitative) rain gauge.  A little reading in the manual for this thing and I've keyed in some instructions that get the rain gauge to function OK (sort of neat, actually, at least to play with).

It reminds me of entering a program on the old PDP-8 instruction by instruction keys, worse than programming in Assembler!

Anyway, having looked through the junk box of stuff I've accumulated over the years but not put to use yet, I came across another RM Young sensor, the 41342 VF temperature probe.  There is a little factory printed sticker on the inside case with that number on, but a little curious that it says "Temp Out: -50F to +150 F = 0 - 5 V DC", since the spec sheet on line for that device number gives a drawing of the electronics board which is identical, and as is the 5 terminal green hook up with the correct wire labeling and matches even the colors recommended by Young, BUT the spec sheet says this is a "0-1.000v" output board.

If you look at the instruction booklet, there are numerous hookup diagrams for the many sensors this thing supports.

There IS a temp sensor that has differential inputs, and is seemingly meant to hook up to their temp input board, the 26726.  The temp sensors that the manual says can connect are 41342, no VF or VC on the end.  These have a different wire hook up to that temperature input board.

To look at the programming, one sees the INP TEMP instruction referencing the 26726 board, and settings to the instruction allow you to specify C or F, and offsets.

Obviously the 41342VF sensor, being a voltage output, wasn't meant to attach to that input board.

Not to fear, I have additional ports on the Voltage Input board.  So I hooked it up, and when I got to the instruction for the Voltage input board there is not all the setup stuff I'd need to make it report temperature to the translator, but it does read the voltage off the sensor and show that as a raw number.

The curious thing is that the instruction for the Input Precip specifies that it will read the Voltage Input board, but the instruction choices indicate that it 'knows' that the voltage is from the self siphoning rain gauge, and must use some sort of look up table to change the raw voltage to mm or inches of rain, etc.

There is no similar Input Temperature instruction that I can find that allows me to do this kind of choice for the voltage input when a temp sensor they supply is used.

I've looked to see if there is a way to hook a voltage output sensor up to the TEMP board, but can't find anything in their printout.

Also, if the spec sheet says this is a 0-1.000v output, why does the little sticker inside the sensor package on the electronics board say 0-5.000 volts out?

Has anyone ever interfaced one of these units, and specifically know how the temp sensor (according to specs is very accurate) with voltage output can be mated easily? 

Just hoping, this is sort of a fun unit to play around with.  I have a wind module too that I think will work and will get a spare 05103 out to fiddle with if I get this working.

Dale
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Offline TheBushPilot

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Dale:

Despite this post being almost a decade old I figure I'd give my two cents. Reckon someone might find this info helpful in the future even if it is an obscure topic.

I do recall you saying you have the newer 26800 translator from Young so this advice may not even apply to you currently.

The 41342VF probe is the voltage (V) Fahrenheit (F) variant of their 1000 Ω platinum PRT temperature probe. These can be configured to output both 0-1000mV (0-1V) and 0-5000mV (0-5V) with jumper(s) inside the junction box. With that said it's only now a matter of finding the calibration curve for the output voltage to temperature. I can't recall exactly but I believe both the 26700 and 26800 translators have 0-5000mV input. Technically the 1V and 5V from the T probe would work. Just a matter of finding that curve for differential voltage input. Since that's a Δ 200F between low and high reading of the sensor, we can deduce a multiplier value of 0.04. 0.2 for 0-1000mV and 0.04 for 0-5000mV.

Then to make this output useful we offset the reading by -50 so that 0mV reads -50F, and 1000mV/5000mV reads +150F.

I assume we are referencing the wiring diagram in the 26700 manual, using the TEMP board and Platinum RTD probe. Should be as simple as matching up the output of the sensor with the input of the board. Matching the temperature measurement type, Platinum RTD resistance, and making sure the offset is correct (-50). Doesn't make any mention of input voltage but I assume that can be easily determined through trial and error.
"There is always more than one thing influencing anything we are trying to measure." ~ Sherman Fredrickson
"Do it right or don't do it at all."

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Offline DaleReid

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Thanks for the reply!
I will go hunt down that sensor and see if there are option jumpers inside on the little round PC board.

I am using the 26800 for most of the stuff, and have one full blown station, even with solar radiation, feeding a Weather Display and runs just fine.

The 26700 has been used mainly for testing out newer parts I've scavanged and to see what I can make it do.  I could use a voltmeter I guess for most stuff but having a fixed box and viewable display seems like more fun.

Thanks for the info, and I'll see if I can get the temp probe (supposedly the most accurate and precise one can get) to work.

DAle
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Offline TheBushPilot

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For sure, any time.

Man now you've got me curious - what are you running?

Specs? Pics? Both?

Sounds like you've got the ideal setup. :grin:
"There is always more than one thing influencing anything we are trying to measure." ~ Sherman Fredrickson
"Do it right or don't do it at all."

Met Instruments Project
VDU Station Data
Central Chasers

 

anything