I recently purchased a digital multimeter from Maplin which was on sales at that time: Precision Gold N56FU. Being a full sized autoranging multimeter with computer interface, this meter £44.99 seems to worth every penny. Of course, Maplin didn’t make this meter. Some Chinese dudes did. Maplin just rebranded the meter because E-SUN sounded too lame =P
No purchase is complete until it is disassembled!
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Nope, certainly no FLUKE board, but still, it looks very solid.
1. The controller: FS9922-DMM4 from Fortune Semiconductor Ltd. You got to love those Taiwanese. They slapped two analogue to digital converters, voltage regulators, AC rectifier, LCD driver, RS232 driver, etc etc…onto a silicon slab. That’s basically EVERYTHING you need to create a modern digital multimeter on a single chip!
2. Infrared LED: If you’re wondering why there’s an infrared LED on the meter, trust me, you’re not alone. I was puzzled as well. Note: I removed the complimenting infrared receiver module for clarity reasons.
3. True RMS converter: AD737J from Analog Devices, which a quoted accuracy of ±0.2 mV. Sweet!
4. 640 mA fuse: To protect the micro/miliampere line.
5. 20 A fuse: To protect the 20A line.
6. Copper jumper: Well, if you want to pass 12 kW of juice through this meter, the bigger this copper jumper, the better.
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Look at the huge fuses!
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The brain!
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True RMS converter
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Infrared LED
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Infrared receiving unit. Notice the Silicon Labs CP2101 USB-to-UART converter chip (2). The IR receiver is located at (1) and the USB port at (3).
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If you were still wondering why on earth did E-SUN used infrareds instead of just hard wiring the the USB-to-UART chip to the controller, consider this: You are conducting a high voltage experiment. Due to budget cuts, your department crossed out FLUKE and gave you an N56FU instead. You hooked the meter up to the 415 V rig and connected it via USB to a £1500 notebook. You took the notebook and went behind the plexiglass shielding for protection.Your computer started charting impressive graphs of the equipment you were working on when suddenly, there was a flash a light and you get thrown ten feet away. Your meter was fried and so was your notebook. The plexiglass shield was still intact though….So what happened? Some incompetent lads wired your rig wrongly! A gazillion volts rained down your meter due to a premature capacitor discharge. The current travelled through the multimeter, through the USB cable, over the plexiglass, straight to your computer! Whao….busted!
Back to business! This is what we call Optical Isolation. The circuitry on the mainboard (1) converts RS232 to IrDA signals and beams it to a receiving unit (2) housed in tough, clear polycarbonate. The IrDA signals are then decoded and converted to a USB language that your computer understands. Note that there aren’t ANY electrical contact points between the mainboard and receiving unit. The circuitry on the receiver draws current from your USB port only, since high voltage electricity can still arc and jump into this circuitry if it isn’t 100% isolated. This way, you and your computer can remain safe (while the meter literally takes all the bashing).
Owing to the fact that this meter can do MORE things than a £150 FLUKE 116, and that SAFETY has been heavily emphasized, I would say this is the most value for money digital multimeter EVER.
January 29th, 2010 at 7:23 pm
Have to agree – they were selling this reduced to £29.99 at local Maplins recently and I think I got the last one. Seems to be well engineered and has great specs.
My only complaint would be it seems slow to equilibrate (maybe this is only on the most sensitive ranges?).
Hopefully this low-pass filtering is absent on the USB uplink, have yet to investigate this.
__Mark
February 12th, 2010 at 10:32 pm
Nice and useful review, I also own one of these multimeters and I am extremely happy about it.
It works with both Linux and Macs, and the USB data stream is easy to read. Sweet! D.
March 6th, 2010 at 8:48 pm
Fully agree. A clever piece of measuring tool it is (was, in my case. I managed to fry my N56FU with a too high of a voltage, most likely static, that it couldn’t take).
April 26th, 2010 at 9:50 pm
I own one this multimeter as well and is working quite good. Unfortunately I lost CD with software for this multimeter do someone have idea where I can download this software (for windows) or maybe someone can upload it for me. thanks
May 5th, 2010 at 11:22 am
Question: When selecting Capacitance, should the meter be showing zero’s, the reason for my question is my N56FU meter is always showning a reading of about 317.00 I believe someone who I work with (he thinks he’s the Oracle) did not bother to discharge the 3300uf cap before tesing it, is there any way I could repair it.
May 9th, 2010 at 3:26 pm
As: here you go http://rapidshare.com/files/385306021/n56fu.zip
john: unfortunately it doesnt seem possible to me. Looks like you’re gonna have to go oldschool with RC circuit and a stopwatch lol
May 18th, 2010 at 8:14 am
Thanks for the info on this dvm. I also bought one when it was on offer and have been very pleased with it till now. However, I just trashed it completely with overvoltage (from an electric fence – utterly stupid thing to do!). I thought there was no voltage on the fence – wrong – I saw a reading on the volts range, and then the display went blank. Disconnecting the battery and reconnecting makes no difference. Have you any thoughts on what might be dead? I cant see anything trashed inside but presumably ESD could have got right through to the main processor chip – can this device be obtained in one offs? Its probably not worth the effort of trying to repair anyway – at least I now have a nice USB serial infrared receiver for another project – does anyone know what baud rate it runs at?
Tony
May 21st, 2010 at 9:59 am
Whao! thank God you didn’t use your fingers to test it though =P
The USB receiver seems to be operating at 2400 baud, 8 bits, no parity, 1 stop bit, hardware xon/xoff.
Hope that helps!
July 9th, 2010 at 8:32 pm
How accurate do you think the temp sensor is on this thing ?
July 12th, 2010 at 8:32 pm
Toby: I’ve calibrated the multimeter against a benchtop thermometer using the same thermocouple before. It appears that the multimeter has rather bad linearity, especially towards the extreme ends of the scale. I don’t have the exact numbers with me but I would say for scientific use = no, for casual use = yes.
July 19th, 2010 at 6:17 pm
Great value for money, I paid €30 for mine (on sale). Although beware when continuity testing -I just spent a few hours looking at a board (pulling my hair out )trying to figure out where a short was only to find out that it considered a 10 Ohm resistor a short, head recking!! Maybe this is standard I dont know….
July 22nd, 2010 at 5:21 pm
Any one know of any software to force it to grab a reading rather than the time interval the supplied software has?
In fact is there any better USB Windows software available for this beast?
Is there a API Dll available for this meter?
July 30th, 2010 at 3:12 pm
I’ve just bought an N56FU but can’t get it to talk to my Windows 7 PC
I’ve tried installing the drivers (winnt) using CP210xVCPInstaller and also run the setup on the CD and repeated the whole thing using a version downloaded from the web. The software runs but won’t read from the meter. I would be grateful for any help/suggestions!
August 1st, 2010 at 11:08 am
Just bought the meter from Maplins but cant get the software to fire up it just gives a demo page with a resistance (ohmeter).
I looked into the drivers and files and it seems to support Windows 98me and Windows NT.
So maybe thats what the problem is, has anyone got a suggestion?
are there any driver updates?
The Maplins guy said I need to buy a battery with it but I installed the one supplied and its got a voltage 0f 9.6Volts off load which seems ok to me.
August 4th, 2010 at 8:50 am
Hi gain – sorry if I seem pushy but I’m nor sure if my lasy query got through (I haven’t had a confirmation) I installed the link software (Windows 7 64bit) but it doesn’t pick up readings from the meter. Does anyone know if it’s a Windows 7 problem or might the meter be faulty? Thanks in advance
August 5th, 2010 at 5:41 am
Dave: I’ve got several of this meters hooked up to Win7 64-bit notebook using driver from http://www.silabs.com/products/mcu/Pages/USBtoUARTBridgeVCPDrivers.aspx . Hope that helps
Gadgetboy: Use the above link for driver =)
Quatermass: I’ve not seen any WinDLLs but Linux modules are available (QtDMM2). You may be able to code a interface yourself using pages 31 onwards of http://www.ic-fortune.com/upload/Download/FS9922-DMM4-DS-11_EN.pdf
August 6th, 2010 at 7:46 pm
Hi LordTCT – Thanks for helping:
I downloaded CP210x_VCP_Win_XP_S2K3_Vista_7 and ran it: it installed in c:silabs\MCU\CP210x\Windows_XP_S2K3_Vista_7 with the following folders: x86 and x64 and the files: slabvcp.cat – slabvcp.inf – setup.ini – Release Notes.txt and CP210xVCPInstaller.exe
I ran CP210xVCPInstaller.exe and it reported a successful install (files appeared in C:\Program Files (x86)\Silabs\MCU\CP210x including the x86 and x64 folders and slabvcp.cat and slabvcp.inf
I then ran N56FU Communications Program V1.52 and connected to COM3(USB)
The program is frozen in a resistance mode, with a reading of around -15 ohms regardless of what I try
I’ve pressed the Rel/USB button on the meter but it just puts it into the relative mode
I’ve tried two connection cables but to no effect. My black probe is in the COM socket and the red is in the righthand-most socket.
Am I doing something silly?
August 13th, 2010 at 1:17 am
You need to push and hold the USB button for a couple of seconds until USB comes up on the screen.
August 14th, 2010 at 4:07 pm
Lord TCT,
how did you hook up more than one meters to you laptop? I have been trying for days without success. I found the n56fu software is not useful for multiple meters. It would not install more than one copy, it would not run two instances either because it uses the same data file. tried a few other ways such as run as different user and start up from different directory, all failed.
thanks for any help you can give me.
daniel
August 16th, 2010 at 10:41 am
Hello Kent,
I’m afraid I’m not the manufacturer of the product so I’m unable to give you detailed troubleshooting steps =(
If I were you I would plug the unit to a PC, switch to USB mode and intercept the signals using a terminal application (such as Hyperterminal for Widows or Minicom for Linux). From there you will be able to see if its the driver that’s giving problems, or the the multimeter is giving you corrupted data.
Cheers!
August 16th, 2010 at 10:48 am
Daniel,
I wrote my own RS232 wrapper using C# (Microsoft .NET) for multiplexing. It’s pretty simple. For starters, you may want to try using WinForm’s the Serial Port component to interface with your meters and once you are able to read the meter’s sentences, you should refer to the manual below on how to interpret them:
http://www.ic-fortune.com/upload/Download/FS9922-DMM4-DS-11_EN.pdf
You’re gonna have to code your own data logger and visualiser of course, but .NET 4.0 has a pretty useful X-Y scatter chart component built in.
August 17th, 2010 at 5:34 pm
Crash Override – Thanks very much! It works. Now I know what I’m supposed to do, I lookedf at page 9 of the instruction booklet where it states . . . Pressing and holding this button for about 2 seconds sets the meter to USB communication mode . . . ! I was initially thrown by page 33 which says that there are instructions on the CD (which there aren’t!)
Again – thank you!
Thanks again Lord TCT for pointing me at updated software!
August 23rd, 2010 at 5:41 pm
Thanks for posting your article and the links. They provide fascinating insights to the innards of this remarkable meter.
Through use, I’ve found that the N56FU has a bug which can rapidly discharge the meter’s internal 9V battery. When measuring with the meter, if you use the screen light, then wait for the light to time off, then press max/min (twice if max/min not previously pressed), the meter draws more than 40mA from its internal 9V battery. The only way I’ve found to stop this high current drain is to move the function switch to OFF.
August 25th, 2010 at 5:05 pm
Thanks for the tips Clive! It should also be noted that the screen light is very power hungry – draining a carbon-zinc battery in just 5 hours on! I think I’ll be replacing the white-ish LEDs with more power friendly yellow LEDs!
August 26th, 2010 at 12:35 pm
The screen light bug can be avoided if the light is turned off manually (press Hold/Light button for > 2 seconds) before the light times off (10 seconds). Once the light has timed off automatically, a subsequent press of any button is likely to initiate the bug causing a high current (>40mA) draw from the 9V battery. Once started, the high current draw continues until the function switch is moved to OFF; whether or not the lamp is on. When employing the manual light switch off workaround, the meter uses about 10mA when the light is on, and 4mA when the light is off.
September 13th, 2010 at 9:01 pm
I discovered recently that the N56FU has a serious bug in the Chart software they include.
If you set it to automatically take a reading every time interval and leave it to record over a period of time it will miss out records.
After painfully watching it over several hours I discovered why.
If the software takes a reading from the meter and logs it and then the next reading is the exact same value it doesn’t record it!
Can you believe it?
I was recording the voltage across a 1.5V battery recovering after being on load over time and I was wondering why the 30 minute chart set to record every 1 minute only contained 22 records!
I’m running V1.52 of the software, if anyone has a different version then I’d love to know and get a copy because as it stands its worthless as a data recording device.
Is there any other USB recording software I can purchase to use with this device?
I’m tempted to stick a webcam on the front face of the N56FU and record its measurements that way!
September 13th, 2010 at 9:27 pm
Hi Lord TCT (Roy),
You wouldn’t have by any chance a simple Windows 32bit x86 executable program that I can run via the cmd line and it captures a reading from this meter and allows me to save the reading into a batch file variable?
That’s about my limit when it comes to programming sadly.
I can be contacted on my web site.
September 14th, 2010 at 5:47 pm
Hi Lord TCT,
I’d like to apology for my last couple of postings regarding a bug in the software of the N56FU.
I’ve discovered that yes by default it removes duplicate readings. But it’s not a bug, its a feature.
There is an undocumented option called ‘Value Repeat’ which if switched on, turns off this behaviour.
Quite why a engineer would use a recording chart and not want all the data recorded as it was at the time is beyond me. Still I’m glad it’s not ‘broken’ as I thought.
You might be interested in what I also discovered which might be useful for users of the N56FU.
I ran PortMon (a free Sysinternal tool) on COM3 and it nicely records the data coming from the N56FU and I was smiling when I saw that the voltage reading is displayed too!
See http://mytriops.com/mypics/portmon_on_n56fu.png
September 19th, 2010 at 2:52 am
Hi Stuart,
Thanks for sharing the tips! Due to widespread request, I’m currently working on an RRDtool based data logger for the N56FU to replace the rather “crude” software bundled with the meter. I’ll be sure that you’ll be the first few to catch a glimpse of it!
Cheers!
September 30th, 2010 at 4:18 pm
Anyone out there with a copy of the N56FU software,I am willing to pay.
Get in touch,cs0012874@blueyonder.co.uk,thanks.
October 25th, 2010 at 4:06 pm
@Lazerenco,
The software can be downloaded from Maplin UK’s website or from:
http://rapidshare.com/files/385306021/n56fu.zip
No $$$ required!
October 30th, 2010 at 11:45 am
Stuart:
If the system records both the measurement value and the time that the measurement was made then there is less point recording duplicate readings. You will need to display your results as an X-Y chart and treat the data accordingly.
November 8th, 2010 at 5:02 pm
Hi all.
I am hoping to integrate the N56FU into some VB.NET software I’m writing. Accessing the data is a little more tricky than I’d hoped.
Why can they not simply tell us the workings of the .dll so that we can access the data?
Other suppliers will (Velleman with vb, C#)
I expected this to come with some example files at the very least.
I mean come on, this appeals to geeks, geeks love to tinker….
Has anyone successfully integrated this thing yet?
The best I can do at the moment is record the time and then retrieve info from a saved .CSV file.
Primitive to say the least….
November 9th, 2010 at 4:56 pm
Hi Revolution Radio,
I’ve written a wrapper for N56FU-like meters in C#. I shall be posting the source codes on this blog soon after I’ve clean up the code.
Cheers
November 30th, 2010 at 5:47 pm
Hi all,
I have purchased multimeter Velleman DVM1200 at 50 Eu (Tax Incl.) and it also uses a similar chip to FS9922-DMM4. Some information can be found in the webpage:
http://www.velleman.eu/distributor/products/view/?country=be&lang=en&id=372236
It is quite simiar toN56FU. It has some differences in the LCD (“RS-232″ is changed to “PC-Link” symbol in the upper left part of the display). To start the USB communications, you have to turn on the multimeter while pressing the “Hz/Duty” key (instead of the “Rel/RS-232″ key).
The transmission protocol is similar to the N56FU, but it is not the same!
I want to collect data from several multimeters to make a measuring system for a laboratory practice (each USB cable appears as a COM port, so you have to interpret the data from the data stream). The software from Velleman only allows to record one multimeter in each instance. There is no source code to derive transmission protocol either.
You can se the 14 bytes from the DVM1200 (it is the line Length: 14 .’=A_g} when it should show the reading in ASCII)
http://www.windygrid.org/VELLEMAN_DVM1200.png
My interest is to perform on-line computations and graphs for educational purposes. I migth modify the code from Lord TCT for operation with Velleman DVM1200.
Unfortunatelly, the exact chip model cannot be seeing since it is covered by a black layer of glue. I guess it is a different version of FS9922-DMM4. The PCB says VA18B 20070302, but I guess it is the revision and the date of the PCB design.
Have anyone the data of the DVM1200?
Thanks.
December 2nd, 2010 at 2:21 am
Hello Joaquin,
I suggest you use REALTERM or some serial port capture software to look at the coms in hex or binary instead of using PortMon. Please do give me a sample and I will have a look at it =)
Cheers
December 8th, 2010 at 12:26 pm
Hi, Just bought a N56FU multimeter, Installed the software. But can get any measurement screen stocked on OHm measurement a -30. I followed all the helps given to other but still not working. I have a window XP and have being using COM6
Thanks a lot
December 9th, 2010 at 5:03 am
hi Eva,
Is the reading shown correctly on the meter?
December 30th, 2010 at 11:28 pm
I have one of these meters and have been using it for about a year. For some reason when the switch is set to measure resistance, the degrees C symbol appears and you cannot measure anything. Has anyone experianced the same problem?
May 23rd, 2011 at 4:49 pm
I have exactly the same problem as Bill whereby the degrees C symbol appears on resistance measurements and OL in the display. Does anyone know a fix for this ?
July 15th, 2011 at 4:31 am
hi i was wondering if any one could help me my meter is reading voltage even though its not connected to any thing its only mv volts but its not help full when trying to read mv readings
any ideas
September 5th, 2011 at 3:17 am
Has anyone found a source for fuses for this meter ?
Maplin says it is obsolete and will not provide them.
The 640 mA fuse seems to have a diode in it ?
September 5th, 2011 at 9:48 pm
Daniel: a 500 mA quick blow fuse wire would suffice
September 30th, 2011 at 6:17 pm
Anybody know how to zero out lead readings before doing a low continuity check on the ohms scale?
November 11th, 2011 at 10:18 pm
Dave:
It is normal to read some mV if the leads are not connected to anything(floating potential). Try to connect both leads together and it should read zero.
Daniel Johnson:
I think that the fuses used in these meters are faster than quickblow (they are class aR – semiconductor protection – Very Fast Acting) and also very very expensive usually between 3-7GBP each.
To make things even more interesting, I have an older N56FU (serial number starting with 3) that has on the board silkscreen printed 630mA/1000V and 20A/1000V and the fuses fitted are 500mA/1000V and 20A/1000V. On a newer one (serial number starting with 5), the silkscreen has the 630mA/690V
and 20A/690V and the fuses fitted are as the silkscreen.
As I recently succeded to blow the 630mA fuse on the newer unit, I looked quite some time to find a replacement. There is a UK based company that makes such fuses but it has a minimum ammount of 150GBP per order.
Failing this, I searched all the usual suspect Farnell,RS, Maplin but theydid not stock them (there was some stock for the 20A one).
Recently I was able to track down the original manufacturer of the fuse and ordered 10 of them for 75USD (including delivery to UK which is 20USD). The company is named HOLLY and it is from China.
The link below gives the specs for the fuse (you can use the same site to contact them)
http://www.hollyfuse.com/uploads/2008-2009%20Cg/HC10aR.jpg
Hope that helps.
November 27th, 2011 at 6:00 am
Hi, I have purchased VA 18B.Have installed soft and drivers for DMM USB-RS232 connection. Choose proper com port.Turned on DMM for PC connection. But on the PC screen there are no tramsmitted data from VA18b. Help me pls. It seems that VA18 is similar to N56FU.