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From: Jeroen Belleman <jeroen@nospam.please>
Newsgroups: sci.electronics.design
Subject: Re: GPIB bus topology
Date: Tue, 7 May 2024 17:43:38 +0200
Organization: A noiseless patient Spider
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On 5/7/24 17:23, Don Y wrote:
> On 5/7/2024 7:16 AM, Chris Jones wrote:
>>>> There is a board which you can get made at OSHpark cheaply which 
>>>> adapts the arduino pinout to the connector.
>>>
>>> What I don't understand is why someone would go to the trouble to make
>>> a daughter card and NOT just add the rest of the necessary components
>>> TO that card and package the whole thing better/smaller!
>>
>> It's to go on the back of a GPIB instrument. It doesn't need to be 
>> small, but it is no bigger than a normal GPIB connector. It uses a 
>> small arduino "pro micro".
> 
> My point is more generic than that.  I am often approached by clients
> wanting to design a "daughter card" to some existing "module".  But, there
> is no *win* to using the module if you're designing (and having produced)
> a daughter card -- it's just another dependency (and constraint) that 
> you've
> baked into your design.
> 
>> If someone had intergated all of the components onto the same PCB as 
>> the GPIB connector I would have avoided that design.
> 
> Why?  Unless you want to be able to salvage the arduino *from* the daughter
> card at a later date.  Eschew unnecessary connectors, dependencies, etc.
> 
>> It is easier to buy an arduino than to build one,
> 
> But, did YOU have to build the daughter card?
> 
>> and probably cheaper too if you only want exactly one of them. The 
>> adapter PCB was very cheap and building the whole thing was very quick. 
> 
> Ah, that answers the previous question.  (I am talking about BUYING
> a product that "does it all" instead of hacking something together)
> 
>> That is what I wanted. I just wanted to back up the SRAM in my DMM 
>> before its battery went flat and lost the calibration settings, or 
>> before I accidentally erase the SRAM in the process of replacing the 
>> battery.
> 
> Understood.
> 
>>> OTOH, learning how to miniaturize entire products is a skill that takes
>>> time to learn.  And, anticipating each potential future "shoe-horning"
>>> activity is a challenge (I have a design that fits in WoW characters
>>> but won't fit in Furbys, to my chagrin!)
>>>
>>>> There are relatively cheap connectors without the jack screws and 
>>>> daisy-chaining capability that you can use because you do not 
>>>> require the ability to daisy chain other cables onto the back of 
>>>> your USB adapter.
>>>
>>> I just used an IDC-terminated connector as my PCB was largeish (old
>>> technology) and didn't want it supported by the instrument's connector.
>>> And, as I said, have tossed the GPIB cables opting for an adapter
>>> per device (I suspect most folks don't really need the ability for
>>> devices to talk to each *other*)
>>
>> Yes, and if you're doing that, it is cheaper to use the arduino 
>> adapters than National Instruments, software permitting.
> 
> Ah, but Arduinos didn't exist in 1988 -- did they?  :>
> 
>>>> One shortcoming it has is that it will draw current from the GPIB 
>>>> bus if the USB cable is not powered, but it is easy to avoid doing 
>>>> that.
>>>
>>> I would eschew anything USB-related; it often requires drivers
>>> and places limits on where the USB host can be located.  E.g.,
>>> I can talk to my adapter from an old SPARCstation, NeXT cube,
>>> cell phone, etc. instead of having to add USB capabilities (and
>>> cable) to each.
>>
>> I don't like USB, but a lot of software and hardware is set up to use 
>> it, so as 
> 
> Now.  But not in the past -- or likely in the future.  In much the same
> way that printer (and, soon, serial) ports went obsolete, consider how
> everything USB-related will fare when The Next New Fad comes along?
> 
>> long as someone else deals with the details of the USB stack and it 
>> works, I won't complain too loudly. If I have to write the low level 
>> software I will try to use something else.
> 
> I've decided that network interfaces represent the future of most
> interconnects.  It's silly to keep reinventing new stacks for each
> different (competing) interface.  Better to standardize on an external
> interface in a device-independent manner.  Look at the mess it leaves
> each time some *interface* is deemed obsolete (just because of the
> specific hardware device that required it)...
> 
> [I'm looking at an external disk enclosure with three different
> interfaces on it when one SHOULD have sufficed.  Or, bare disk
> drives with ST506, ESDI, IDE/PATA, SATA, SCSI, Wide SCSI, SCA,
> FC-AL, SAS, etc.  Needless variety.  And, that's not to mention
> the cabling involved!]
> 

The variety is there because of a long history of changes to
induce people to buy new things. Thus it will ever be.

Jeroen Belleman