John Smith 72-6870 protocol Tenma / Uni-Trend support info

Hi John, please forgive me on this minor joke, but I could really do with a pint! Now you can have a laugh at the appellage they gave me!

Now to serious business, You posted on Google group long time past, I found the message today, and I am so glad I never plummed for a data meter that needs a computer. Everything to digital is such a =A0hacked up situation, sometimes I don't know who the devil to believe. This message took me 30 minutes to post, because google could not sort it out with the browser reponse. So I have had to use my mail account.

What I found out from reading FEC Farnell is they sell a Tenma multimeter which is exactly like a multimmeter I bought from Maplins.

Theirs is farenheight, and mine is celcius, so it looks like I got the right item, cos farenheights would do my head in, and thats is all the difference, oh and the colour, its red and gray. not yellow gray. Style wise it looks the same.

I read through the post. I got to the bit where it says go to

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Been there done it, never saw no page, AS PER USUAL

How did you get on with that, I went to the site, and nothing showed up at all, was that the truth for you?

Google searches show up two links relating to companies called tenma, ones up north Uk doing injection moulding, the other is in japan in the same buisness injection moulding. Seems like tenma are a great brand in the plastics business!

Who is the clown exactly? FEC say Tenma respectable big large maker of measure. . . . =A0in fact 2002 their catalogue lists their products, seems they do quite a bit, nothing shows up for a HQ appart from distributions suppiers. Its a badge label scam.

I down loaded the tenma manual for the equivilent of my meter from fec to look at to see if I can get some sense on the probes: I got an issue of a confusible with tempreture probes, you see, =A0the speck says nick chrom silicon nick silicon, and says its K type but should be N type, the colour indicate a J iron typ or an I don't know my ass from my head ,with it. The wrong spec of probe gives a 40 degree out error at 440 degress.

An I don't know the top tempreture, it says 1000, but the probe don't look as though it can handle much more than 250 C.

What I found is that the FEC manual is a hacked up version of the Uni-trend, they been through the manual changing centigrades for farenheights, and there are mistakes in their doing that, some oversights in the manual.

So heres the correlate:

The temax 72-7930 is a Uni-trend 58C device but set to farenheights.

Appart from clearing up the issue with tempreture spec the only mistake is on one page that should read display shows the mv scale.

So having cut out the nonsense in the first line, you should now be in a clear position to be able to cross ref your model of meter in the uni-trend range, and ask direct for the protocol from their factory in china, like I am doing about finding the probe tip they ship out.

I am sorry you have had such trouble with this interface problem, and have emailed you with some straight info as soon as I read the thread.

The FEC spec on probes is good, and informative, its just the probes don't match the classes of products, and theres three different areas of confusion in the spec sheet in the manual. Its important to know materials, and length of cable will affect voltage, and therefor reading of temps will differ according to probe materials and lengths.

So what I can offer in advice is that my meter is a Uni-Trend meter, and that is the same base factory production as uni trend meters.

I found them! They are at

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They got an address in =A0Rm 901 9/F Nanyang Plaza 57 hung To Road Kwun Tong Kowloon Hong Kong.

I got email

And =A0phone and fax (852) 2950 9168 (852) 2950 9303

What you need to do is visit the unitrend site, find the spec of the model of meter Tenma you have, and that looks the same is layout and style, and spec, and post them a request for the protocol.

Your right, Tenma ain't metrix, but its close enough to Unitrend to have the same guts, and protocols.

Check it out, let me know how you get on, and if you find anything about tempreture probe specs, I would sure like to know the spec of the probe that ships with BOTH brands of the item.


Dr David Christmass

John Smith wrote:

Hi. If I am in the wrong newsgroup, please forgive me. > > I bought a Tenma 72-6870 from MCM to use in a closed-loop temperature > controller I was constructing. I was unaware that the protocol for the > communications would not be available in the instruction manual. Worse, M=


will not release the protocol. This makes the meter unusable for my inten=


purpose. I have partially decoded the 14-byte string , but have had probl=


decoding the rest. > > Can anybody help with the protocol? TIA. > > John
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