To Upload or To Download

castlerock said:
Does anyone have any idea why the terms upload and download are backwards when talking about plc's ? Uploading has always been to send a file and downloading has always meant to retrieve a file from a remote computer. If I send my program from a laptop to a plc, that would be considered uploading on any other platform.

I agree completely, the terminology used by most PLC manufacturers is backwords! But just like the QWERTY keyboard, someone made a bad decision at some point and we are stuck with it. :)

By the way, anyone ever used the Reliance Electric Automax DCS system? In that system, an Upload writes to the controller, and a download reads from the controller. That makes much more sense to me.
 
Steve Bailey said:
How's this for an explanation?

If I'm writing the PLC program on my laptop, I'm in charge of that progrom. I'm the boss. The boss' office is in the penthouse, not in the basement. So when I (the boss) send the program I've created to the PLC (the subordinate), the program is going from my office in the penthouse to the PLC. The path from the penthouse to wherever the PLC is located is downhill, so naturally, that's a download.

I believe that thats actually where the term originated. In the early days of mainframes and networking people sent data "up" to the mainframe or retrieved data "down" from the mainframe. But I'm also under the impression that mainframes were usually in a basement. Computer engineers don't always make sense and tend to have an odd sense of humor. For instance, I have an assembly language book where the author talks about a blue card ( a reference card for low level cpu instructions ) that was bright orange.

Sometimes it just doesn't pay to try and make sense of things. =]
 
Up & Down

:p From my little brain (also I agreed with some answers here )

Upload = read program from plc to computer or Programming device

Download = write program from computer or programming device to PLC
 
Steve Bailey said:
How's this for an explanation?

If I'm writing the PLC program on my laptop, I'm in charge of that progrom. I'm the boss. The boss' office is in the penthouse, not in the basement. So when I (the boss) send the program I've created to the PLC (the subordinate), the program is going from my office in the penthouse to the PLC. The path from the penthouse to wherever the PLC is located is downhill, so naturally, that's a download.

Conversely, if I want to check on the program that my subordinate is running, I invite that subordinate to "come on up to my office", in other words, upload.

Nice analogy Steve :)
 
this is a bit complicated. does the sun circle earth or the other way around?
for centuries people believed first...until they got smarter. i guess learning
or using proper terminology is also moving forward. :)
downloading or uploading has nothing to do with location of human initating transfer,
or his/hers relative proximity to one or the other node on the network,
or what status particular node has on a network (master/slave) or else.
(btw. point-to-point is still a network).
download simply means transfer to target node. when you download mp3 or servicepack from internet,
your PC is target device (internet and it's servers are just a tool). it doesn't matter where you are.
when you download program to plc, your laptop and programming cable are just a tool. target device is PLC.
upload is transfer in the other direction (from the target).
 
benanna said:
But just like the QWERTY keyboard, someone made a bad decision at some point and we are stuck with it.

Actually there was a way better keyboard before the QWERTY layout. The problem though was the mechanics were not up to the ability to type fast, so the QWERTY was invented to slowdown typests so they wouldnt jamb the mechanical typerwriters.
 
elevmike said:
Personally I like the way Directsoft has it termed. "Save to Disk" or "Save to PLC" and "Copy PLC to Disk", or "Copy Disk to PLC", that's pretty clear.

Personally (no matter what everybody else goes by), I Upload to the PLC, and Download from the PLC.

I'm one of those odd ball computer networking guys that wound up writing PLC software for a living...

I agree with Mike, DS has the best terminology I've heard for the PC <-> PLC connection; simple and clear.

From a network perspective data leaving a device is upload and data entering a device is download regardless of which device initiated the transfer. When you connect to the net and get your email your computer is downloading information from a mail server; at the same time the mail server is uploading information to your computer.

Communication between your PC and PLC is still a network even if its a simple network of only two devices. When you move a program from your PC to the PLC your PC is uploading information, but the PLC is downloading information.

My guess as to why most of the PLC manufacturers chose to call moving a program from the PC to the PLC 'downloading' is that when PLCs first came out the people programming them typically had very little to no computer experience; the PLC was easy for the first programmers to comprehend and think about, but the PC was just a scary object they had to touch to make the darn PLC work; hence the term downloading; they were really thinking as if they were always inside the PLC, not the PC.

Just my 2c though.
 
I'm amused by those people who insist that there is a "proper" usage of the terms upload and download.

Language was invented by people and terms mean what they are defined to mean. If you are going to practice in a field, then it's up to you to learn the jargon of that field. To complain that the usage of some terms doesn't comply with the usage to which you are accustomed is an exercise in futility.

Take Paul Lucas' signature line as an example.

There are 10 types of people in this world. Those that understand binary, and those that don't.

If you insist on interpreting it through the more common usage of '10', you won't get it, but interpreted as intended, it makes perfect sense.
 
panic mode said:
this is a bit complicated. does the sun circle earth or the other way around? :)

The sun goes up and down. (just kidding =])

panic mode said:
(btw. point-to-point is still a network).

Oops. I meant to say peer-to-peer. Thats still networking but to topology is different and that changes some of the terminology. For instance copy instead of upload or download.

panic mode said:
download simply means transfer to target node. when you download mp3 or servicepack from internet,
your PC is target device (internet and it's servers are just a tool). it doesn't matter where you are.
when you download program to plc, your laptop and programming cable are just a tool. target device is PLC.
upload is transfer in the other direction (from the target).

I see your point. But a target will change. When I upload a file to a ftp server, it then becomes the target. A bullet never travels from the target to the gun. ( thank goodness )

I've just accepted that everything is seen from the PLCs perspective. The laptop is the server and the PLC is the client. Then when a file is sent from the laptop to the plc, it is then a download.
 
marksji said:
My guess as to why most of the PLC manufacturers chose to call moving a program from the PC to the PLC 'downloading' is that when PLCs first came out the people programming them typically had very little to no computer experience;

the PLC was easy for the first programmers to comprehend and think about, but the PC was just a scary object they had to touch to make the darn PLC work;
QUOTE]

Marksji,
First of all, when PLCs started to sprout, the computer (mainframe) was an extremely rare comodity, let alone a PC (which I believe didn't exist at the time!), so PLC programmers could not have had computer experience.
Re. your second point, you've obviously never used a hand-held programming console - Jeez, now there's scary :eek:
 
Steve Bailey said:
I'm amused by those people who insist that there is a "proper" usage of the terms upload and download.

Always glad to be of service. =]

Steve Bailey said:
Language was invented by people and terms mean what they are defined to mean. If you are going to practice in a field, then it's up to you to learn the jargon of that field. To complain that the usage of some terms doesn't comply with the usage to which you are accustomed is an exercise in futility.

I wouln't think of writing AB to complain about thier use of the terms. But I will never stop asking why. I have never received any formal training in anything. I read a lot and ask questions to people who know more than I do.

Steve Bailey said:
Take Paul Lucas' signature line as an example.

If you insist on interpreting it through the more common usage of '10', you won't get it, but interpreted as intended, it makes perfect sense.

Yes. I have the t-shirt. I get a lot of blank stares when I wear it but people who are curious enough to ask walk away knowing that there's more than one number system. I have to respect those people for asking.
 
Paul; you are correct the advent of the PC was after the first PLCs; I guess I should have stated that a bit differently.... I was talking about when PLCs that could be programmed with something other than a hand held programmer first came out. The guys that knew PLCs at the time knew very little to nothing about the PC. Sorry for the confusion.

You are mostly correct on the second part; I've used a hand-held programmer, but only to clear a fault on an Omron C28K. I can't even fathom how long it would take me to write a program similar to what I write daily using a hand-held programmer.

Steve; there is a 'proper' usage for the terms 'upload' and 'download' in the world of networks (which I already pointed out is what you have between a PC and PLC). In the world of PLCs the terms are at best confusing and at worst flat wrong, but you are also correct that language and jargon of a field needs to be something you learn if you plan to work in that field. I'm not advocating that we change the way the well established PLC manufacturers choose to use the terms 'upload' and 'download'; I'm just trying to point out that there is a well established way those terms are used in general when talking about networks (IP ethernet, IPX ethernet, RS232, RS485, USB, whatever) and that the PLC field doesn't always seem to use them that way.
 
ControlMicrosystems Telepace software, used to program their SCADAPack series of PLC's uses "Write to Controller" and Read from Controller"
(Controller = PLC)
 

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