Unlocking’ RS232 output from CyrusTek IC multimeter - Page 1
Forum section: electronics / general

author: Polossatik
author_rank: Frequent Contributor
timestamp: November 30, 2010, 05:17:27 pm
content: Blogger Craig had a look at CyrusTek datasheets and found on how to get RS323 data from cheap meters"There is a band of products within the handheld multimeter market which, regardless of the manufacturer, are all based around an IC family from Taiwanese manufacturer CyrusTek. You can see this in Dave Jones’ multimeter teardowns – nearly all the units he opens up have a CyrusTek IC running the show. So in terms of feature sets they are all on a fairly level playing field; the price spread mostly comes from build & component quality and the user interface design.If you read the datasheet for those ICs – the ES519xx series – you’ll make the interesting observation that they all do RS232 compliant output. So a vast number of multimeters – quite possibly yours - are capable of serial communication, but most manufacturers don’t break it out to the front panel for you"For the rest please see here. TroughHackadayMight be usefull for people who want to use these multimeters as cheap logging devices...

author: Psi
author_rank: Super Contributor
timestamp: November 30, 2010, 09:00:49 pm
content: yeah, i did this to my meter 5 years or so ago.Uses ES51986 chip.Button to enable RS232 is hidden under the case between the other 3 buttons, when pressed the IC starts spitting out serial data on one of its pins as 0 - 3.3v uart.On these models without rs232 they use the same internels and just cut off the top of the gray rubber for the rs232 button so a plastic case without this button hole can be used.You just need to cut out the plastic and you can press the remaining rubber button with any small object.Then you can wack in a max232 and opto to get the serial data from the IC pin to your serial port.

author: Unknown
author_rank: Unknown
timestamp: November 30, 2010, 10:37:21 pm
content: I would strongly recommend using an isolated interface like an opto-coupler (PC side could probably be powered from the RS-232 signal). If you directly connect it to your computer, the common jack will be grounded through your computer, like an oscilloscope. This could result in some serious sparks and damaged hardware if you connect the common lead to something else (eg. mains).Also keep in mind that doing something like drilling holes in the case will void any IEC61010 certification, so I wouldn't even consider using modified meters for anything but <50V CAT I unless you consider yourself able to build to IEC61010 specs. The case is an important component in preventing the user from coming into contact with dangerous potentials and containing blown up components, at least in a properly designed DMM.Apart from safety issues, it's obviously a neat hack.

author: NiHaoMike
author_rank: Super Contributor
timestamp: November 30, 2010, 10:45:32 pm
content: Use a reed switch to activate the RS-232 and some sort of wireless interface. Then you don't need to modify the case.

author: tyblu
author_rank: Frequent Contributor
timestamp: December 01, 2010, 02:14:33 am
content: Quote from: NiHaoMike on November 30, 2010, 10:45:32 pmDon't think you'd want to be transmitting from inside your DMM as it will raise the noise level considerably. I did see one who stuck a transistor driving an IR LED onto the serial line, which seems pretty neat.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: December 01, 2010, 10:28:48 am
content: Quote from: tyblu on December 01, 2010, 02:14:33 amAs long as antenna positioning is sensible this shouldn't be an issue - any meter should tolerate 3V/m from outside - unless you're sending a long distance, a small wireless module won't get anywhere near this.

author: saturation
author_rank: Super Contributor
timestamp: December 01, 2010, 04:15:56 pm
content: Its a great hack, but as alm says, PCs don't have any input protection on serial inputs and it could be a disaster if even a small transient came through.Quote from: alm on November 30, 2010, 10:37:21 pm

author: Neilm
author_rank: Super Contributor
timestamp: December 01, 2010, 06:22:02 pm
content: What you could do (if you can get it to fit) is build a small IR transmitter. It will probably go through the plastic. I have seen this used on some old multimeters (now discontinued). You had to remove it from the rubber housing then clipped on a separate reciever. It talk to the PC to allow the PC to datalog, or you could set it up to datalog as a stand alone unit.It was fairly basic as far as data aquisition goes, with a reasonably small memory and low data rate but hey - it was made about 8 - 10 years ago.Neil