Products > Test Equipment
New EEVblog BM786 Multimeter
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AVGresponding:

--- Quote from: bdunham7 on March 26, 2021, 07:07:53 pm ---
--- Quote from: NoisyBoy on March 26, 2021, 06:45:08 pm ---compared to the old 34401A.  They provide regular firmware update without the need to recalibrate.

--- End quote ---

I can't imagine what you would want to update on a 34401A.   :)
Adding features is a nice idea, but I'm not so thrilled about manufacturers shipping half-baked stuff knowing they can maybe fix it later if they have to--if they are still around and if they still care. 


--- Quote ---Dave, I like the meter, perhaps one thing you could communicate back to the manufacturer is the ability to do field firmware upgrade would have provided a great differentiation that all buyers would love to have, and helps to reduce their warranty cost.

--- End quote ---

I think the issue is that they want their code protected.

--- End quote ---

I think UEI were are pretty protective of the 121GW software, still has a firmware update facility. Probably more to do with the cost of including the physical parts to enable connecting to whatever update media is used.
IanB:

--- Quote from: NoisyBoy on March 26, 2021, 06:45:08 pm ---Dave, I like the meter, perhaps one thing you could communicate back to the manufacturer is the ability to do field firmware upgrade would have provided a great differentiation that all buyers would love to have, and helps to reduce their warranty cost.

--- End quote ---

From Joe's testing experience, it seems the firmware is burned into ROM. I suppose that making the firmware field-upgradable would increase the manufacturing cost. They can't provide an external USB port for safety reasons, and few people would be able to open up the case, connect to an internal programming header, and use a special programmer to burn the new firmware (at the risk of bricking the device if they got it wrong).

Somehow I imagine it just isn't practical to provide a user-upgrade path.
bdunham7:

--- Quote from: IanB on March 26, 2021, 10:49:07 pm ---They can't provide an external USB port for safety reasons, and few people would be able to open up the case, connect to an internal programming header, and use a special programmer to burn the new firmware (at the risk of bricking the device if they got it wrong).

--- End quote ---

For some reason I thought this meter had PC-COM.  But are the PC-COM equipped Brymen meters
 flashable?
NoisyBoy:
I certainly am not proposing putting in a field upgradable design just to enable the ability to deliver poor quality firmware.  And I can certainly understand the challenge in adding such capability.  My point is just that if it is feasible, it would be a nice feature to add. 

I also agree with the 34401A stability, I have two with the final firmware, and those meters are rock solid, but that came with a decade + of updates.  Mine has the final firmware, version 11, I am not sure how much was fixed in the previous 10 versions, but clearly even in the case of 34401A, HP/Agilent saw a need for firmware upgrades over the years.  However, in the case of the 3446xA, they were able to add capacitance measurement to the early build later on, and each firmware release addressed uncommon problems that I will never encounter in my use.  It is nice to know that I have patched it so it will not happen to me if that use case were to come up.

Anyway, back to the 786, I was able to get some random numbers to come up by shorting the leads, but with 50+ attempts on those ranges, I was never able to get an erroneous reading that last for more than a second.  They were all transient readings that lasted for less than 1 second. 

I can actually make the same behavior occur on my Fluke 179 with the latest firmware in manual range.  With the two 34401A I own with firmware 11-05-03, they also generate a split second random reading in manual range.  The only difference is these meters goes back to 0 faster, where 786 could sometimes takes close to 1 second. 

The only meter that shows the right reading in manual range are the 34461A and 34465A, they both display the proper value at every try.
rsjsouza:

--- Quote from: NoisyBoy on March 26, 2021, 06:45:08 pm ---I just love Dave’s transparency and integrity when it comes to product info from the EEVBlog store.
--- End quote ---
He learned from the 121GW revision being sold on his shop with an old HW revision board - not saying he did this on purpose, but it annoyed a bunch of people at the time.



--- Quote from: NoisyBoy on March 26, 2021, 06:45:08 pm ---Unfortunately, based on Joe’s video, it is not field upgradable and a recalibration is required by Bryman.  That is one reason why I like bench meters like the 3446xA compared to the old 34401A.  They provide regular firmware update without the need to recalibrate.
--- End quote ---

I doubt Brymen is using OTP, but instead Flash with a burned JTAG fuse to prevent any access. That said, I recall Dave saying they were pretty tight in memory, which makes sense as a reflasher via serial requires a small bootloader which consumes memory. A ROM bootloader could be used, but it would be easier to hack.

They are not the only ones: Fluke also does not allow this. Keysight does.
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