[RESOLVED] Multiple barcode scanners, single PC

[Dave Sell]

All,

Not sure the best forum for this. We need to connect about 8 barcode scanners to a single PC application. This application needs to know all the barcode scanner inputs, and which scanner did the scan.

In this situation, each scanner is intended to direct the application in different ways. For example, scanner-A would tell the system to begin process-A, and scanner-B would tell the system to begin process-B. Sorry to be so vague, but I'm trying to get to the problem.

This being 2008, of course we are using USB scanners. They all seem to do keyboard emulation, as if 8 keyboards are plugged into the PC. This leads to 2 problems:

1) How to distinguish between each scanner's input, and
2) How to keep each scan seperate, so that 2 scans do not read in at the same time.

Problem 1 can be solved by pre-pending special characters into each scanner's scan data, so the application can know which scan came from which scanner.

Problem 2 apparently cannot be solved. Since all the scanners emulate the keyboard, there seems to be no way to prevent scanner-B from beginning a scan transmission before scanner-A has finished.

I believe the "multiple scanners using USB keyboard emulation" can be solved by not using USB devices, and using RS-232 scanners instead.

I have not seen more than 4 COM ports on a PC, but it seems XP can support up to 256 COM ports. I have 2 free PCI slots, so if I could find some cards with 4 COM ports on them, I might be able to get 8 RS-232 scanners going on the PC.

Anyone else encounter this problem? I can't be the 1st guy to hit this problem, and I can't believe I need to buy 1 PC to support 1 scanner.

Any ideas, advice welcome.

[szlamany]

Can you make the scanners send a single character and then a delimiter to that as well?

So if it scans *123* it sends x*x1x2x3x*.

Also keep in mind that the drivers for these products are created in software houses - find out who did the driver and give them a call. They would probably modify the drivers to handle this for you - for dollars you would think.

[Dave Sell]

I've been in contact with tech support for long preiods of time over this.

Your only software option seems to be <PRE-CHAR>xxxscandataxxx<POST-CHAR>

This is how we were determining which scanner was sending data. However a new problem arises when 2 scanners scan at the same time.

For example, if the scan from scanner-A is like:

A1234567890<CR>

and scanner-B looks like:

B1234567890<CR>

it is, unfortuately, possible for the 2 scans to clobber eachother, looking something like:

A1234B1234567890<CR>67890<CR>

Notice the '5' is missing from scanner-A. This is the problem that apparently has no solution when using USB scanners. RS-232 scanners are not susceptable to this problem, as each data stream is serperated by a hardware layer.

[szlamany]

That was why I asked about the single-character transmission with a "tag" or "marker".

If the "x" marker is in front of every character from scanner A - and maybe "y" for scanner B - then you can reassemble the mess in code to see what came from A and what came from B.

Does tech support know who wrote the driver? Did they do that in-house or purchase it from a shop?

Do you feel like writing a driver

[Dave Sell]

No I'm not going to write any drivers LOL!

The only options are PRE-pending and POST-pending characters to a completed scan, but do not solve the clobber-problem.

Also, I believe your propsition won't solve the problem, as some characters go missing in the final clobbered message. The only real option seems to be to trigger a re-scan if I can tell a scan went bad. However this is all machine-driven using robotics, and re-scans are not always an option when parts go flying by.

[szlamany]

Can you get it to send the scan like 3 times? So you can check each one - kind of like a cheesy check-sum.

[Dave Sell]

No, its going to be a single scan as things pass by a mounted scanner. You only get 1 shot to do a barcode-scan.

I feel like I have no choice but to see how many COM ports I can support on the PCI bus unsing some kind of multiple COM-port PCI card. I only have 2 free PCI slots so I'm hoping to find a 4-port RS-232 card...

[szlamany]

Are you in control of what appears on the barcode itself? The physical paper/label of barcode.

[Dave Sell]

No the barcodes are all laid out already.

this card might do the trick, but we REALLY want to stick with USB if possible:


PCI Serial 8000 Plus - Serial adapter - PCI - RS-232 - 8 ports - JJ-P08611-S5

[riteshjain1982]

not sure to what extend this will help you,but may be you can use 8 socket or object of RS232 class that will going to listen to each serial port and capture the Read event so u will get data and info about which port has sent what data.

[Dave Sell]

Yes, I do believe I can get past this problem by switching to RS-232 scanners, but for political reasons, I would prefer to solve this problem using USB scanners if possible.

[riteshjain1982]

well never worked with USB but can u listen\trace the data coming from USB port?,if yes than u can use same logic that can work with RS232

[Dave Sell]

no, you can't because all the data comes in as the same keyboard input. There is no way to differentiate which scanner send data to the keyboard buffer.

This is unlike RS-232, which you use a different device to listen to each COM port buffer.

[Dave Sell]

UPDATE:

Multplie USB barcode scanners on the same PC using "keyboard emulation" are indistinguishable from eachother. When any of them do a scan, the input gets stuffed into the messaging queue as keyboard input strokes, but 2 simultaneous scans can clobber eachother, resulting in lost and amiguous data.

SOLUTION:

The scanners I am using are from Symbol, and owned by Motorola. An SDK called "Motorola SNAPI SDK v3.0" is downloadable here. Using the included sample C# project, I am able to place the scanners in "SNAPI mode" and the use SNAPI.DLL to distinguish each scanner's input.

[szlamany]

Nearly doing your own driver

I'm glad it's working for you!

[Dave Sell]

Thanks! The driver was done for me by Motorola - I just didn't know it existed until today. Now I just have to figure out how to use it in VB land...

[szlamany]

We recently worked with a cash drawer, mag stripe reader and pos-barcode gun using a truly intense point-of-sale driver - took many hours just to get a simple understanding of how it all worked. At least it was documented - reasonably at any rate!

[nilesh11]

Thanks! The driver was done for me by Motorola - I just didn't know it existed until today. Now I just have to figure out how to use it in VB land...

hi,
I m facing same problem with 8 Symbol scanners connected to single PC. can u please post link where you got drivers ?

thanks in advance.

[szlamany]

Welcome to the forum

That link you asked for is in post #14 - hope that works for you!

[Dave Sell]

Yes, but take note:

Listed below are the scanners supported by the Motorola SNAPI SDK v3.0:

DS3407, DS6607, DS6707, PL4407, MS4407, PL4507

[Jenner]

Good to know! I knew some dumb-mode scanners had advanced APIs that you could directly access, but didn't know which ones. Splitting off incoming keyboard inputs is always a pain in the rear.

[Dave Sell]

Also take note: I spent much time modifying the driver to handle multiple scanners the way I needed it to. I am up to 32 USB SNAPI-mode scanners per computer!

As downloaded, I think you can only talk to like 10. Also, I think you could only react to 1 of the 10 at a time. I needed to react to all of the scanners all of the time so therein lies my modifications.

[nilesh11]

hi,
thanks for reply. I have motorola Symbol LS2208 scanner. which is not supported by motorola SDK. what should i do now ?

[Dave Sell]

You will need to call Symbol/Motorola tech support.

[Eko Mas]

Hai guy...
I Eko...

How to use 2 Symbol Barcode Scanner LS2208 in 1 PC intergrate with VB 6.0 and want separate the data?

Thanks..

[Eko Mas]

Hai..

Where to find snapi.dll?

Thanks

[Dave Sell]

I called symbol tech support, owned by Motorola then they sent it to me.

[avagyan]

Hi guys, found you by googling, (sorry don't have much VB knowledge, except some VBA) may be you can help. I want to connect many PS2 barcodes to one computer. Even if I do it somehow, is there any way to distinguish the scanners without programming? Meaning is there a way to tell, say excel, to assign to each scanner its own column.
What about the bluetooth scanners? Can they do the work?
Are there portable scanners (I don’t want expensive windows CE based) which can store and later at the end of the day sync to the main computer? I don’t need realtimity.

Thanks

[Dave Sell]

PS2 barcode scanner? This refers to the connector type?

Who makes the bluetooth scanners you refer to?

For multiple barcode scanners, I found USB is the way to go. However, you may need access to an API and access them via SNAPI mode.

As per my posts, I used a specific brand/make/model and was able to acquire and modify a driver/API. Then, I can definately tell one scanner apart from the others (I use 36 on 1 PC today). Then yes I can dump each scanner to a column in Excel.

So, yes it can be done, but no, it's not exactly easy.

[Dave Sell]

Hai..

Where to find snapi.dll?

Thanks

Here is the download link. I forgot I had posted it earlier...

[avagyan]

PS2 barcode scanner? This refers to the connector type?

Who makes the bluetooth scanners you refer to?

For multiple barcode scanners, I found USB is the way to go. However, you may need access to an API and access them via SNAPI mode.

As per my posts, I used a specific brand/make/model and was able to acquire and modify a driver/API. Then, I can definately tell one scanner apart from the others (I use 36 on 1 PC today). Then yes I can dump each scanner to a column in Excel.

So, yes it can be done, but no, it's not exactly easy.

Thanks for your prompt reply.
In our possession we have many old barcode scanners, they come with the old big keyboard connector and the adapter to relatively new PS2 connector, but not USB. May be I can use USB to PS2 keyboard adapter, but I haven't tested it yet. I'll try to connect them to USB ports and switch to SNAPI mode you've suggested. Our barcode readers are Metrologic, IIRC
The bluethooths are kinda expensive, don't know if we will be able to buy, but seemed to me that could be better without 36 (in your case) wires. Even better may be tehre are wifi solutions available like in the department stores...
Thanks agian, I'll post back if I'll succeed.

[93lt1]

Dave,

Any chance you would be willing to share a couple snippits of what you came up with on your journey of integrating the SNAPI dll into your VB app? Where you using VB6.0 or one of the .NET versions?


Thanks for any help you're willing to give!

[Dave Sell]

Dave,

Any chance you would be willing to share a couple snippits of what you came up with on your journey of integrating the SNAPI dll into your VB app? Where you using VB6.0 or one of the .NET versions?


Thanks for any help you're willing to give!

What scanners do you have?

[93lt1]

The application I am working on is fairly simple, I am using a single DS-6707. I found the SNAPI SDK, downloaded it and find all the sample source to be VC#. I am not particularly strong with VC# or integrating a dll such as this into VB unless there is well documented VB sample code. I searched the internet with very little luck but ran across this thread.

I am really just looking for the basics. Looking for an event in my app when there is data available from the scanner.

Hopefully this makes sense?

[Dave Sell]

I re-wrote the C# app that comes with the download. If you dig into the C# code, you will find the place where the barcode scan is detected. What I did was create delegates to "Raise Events"

Then, I referenced the Assembly from a VB.NET app, and created an Object of that type. Then, I simply listened to the Events as they came in. I am not sure if I have access to that code.