Communicate to COM port (modem)

Hi guys (and gals)

I am generally not a very technical programmer so feel like I am beating my head against a wall, I hope that you can shed some light...

My problem is that I am trying to pop open a cash drawer wich is connected to my machine via COM3 (my modem port) Now it seems quite a simple task you send a character or two to the port/drawer and it pops open.

I am trying to do this via vb.net at the moment (but have tried hyperterminal and dos to test unsuccesfully) I think Ive got the connection to the com port as a little icon pops up in my taskbar displaying to that affect but doesnt show any bytes moving around. So I think that my problem lies in writing to the port correctly?

here is an example of VB6 code they suggest you can use...

Code:

---

Dim IntFreeFile As Integer
'Set IntFreeFile to the next available file number
IntFreeFile = FreeFile

'Open the parallel port with #IntFreeFile
Open "LPT1" For Output As #IntFreeFile
'Print to the parallel port, This is the line that fires the drawer.
Print #IntFreeFile, Chr$(27) + "p" + "0"
'Close the port
Close IntFreeFile

---

Here is the code that I am trying to write to the port with in .Net

Code:

---

        Dim dt(255) As Byte
        Dim written As Integer

        Dim AE As New ASCIIEncoding
        Dim count As Integer = 0

'-- Was using all these characters to test...
        For count = 0 To 255
            dt(count) = AE.GetBytes(Chr(count))(0)
        Next

        'Check if our comport is open
        If Opened = True Then
            WriteFile(hPort, dt, 256, written, Nothing)

      '-- Etc..

---

Has anyone done anything similar? Any advice? even maybe how to do this via Hyperterminal or something...(im getting desperate!) :P

You have something confused. You said that you have the drawer connected to the COM3 port, but the sample app shows the Parallel Port (LPT1:). Their method writes directly to the parallel port.

This should work for XP, but you also might want to try just using

VB Code:

Printer.Print Chr$(27) & "p" & "0"
Printer.EndDoc

Which will send the command to the printer. If the printer also has has a com connection, then you would have to write to a file to open the drawer.

What kind of connection do you have? Is it a printer and cash drawer?

Does it have a small round connector (com port) or a big rectangular (parallel port) or does it have both?

Quote:

---

Originally Posted by dglienna

You have something confused. You said that you have the drawer connected to the COM3 port, but the sample app shows the Parallel Port (LPT1:). Their method writes directly to the parallel port.

This should work for XP, but you also might want to try just using

VB Code:

Printer.Print Chr$(27) & "p" & "0"
Printer.EndDoc

Which will send the command to the printer. If the printer also has has a com connection, then you would have to write to a file to open the drawer.

What kind of connection do you have? Is it a printer and cash drawer?

Does it have a small round connector (com port) or a big rectangular (parallel port) or does it have both?

---

dglienna, your code will not work since this is .NET code and not VB6 code. There no longer is a Printer object in .NET.

Quote:

---

Originally Posted by shenku

Here is the code that I am trying to write to the port with in .Net

---

The COM Port is a D-shaped 9 Pin connector.

Well, there were a few things wrong with this, and I showed the vb way that it might work as well, but if it didn't work in HyperTerminal either, I thought that the port being used was the issue. That would be the place to start, before porting to Net, which I leave to the Net guru's

I have seen cash drawers with parallel and serial ports, that is my main concern

the keyboard and mouse are serial devices. rd is right about the com connection on the pc being d-shaped.

if you are using a USB port, there could also be issues... :eek2:

The vb6 code example was from the manufacturer's suggestion. I think your main concern should be to solve
the issue at hand in the language requested by the thread starter.

Anyways...

shenku, what are your parameter values for hPort? Edit: and writen?

VB Code:

WriteFile(hPort, dt, 256, written, Nothing)

This is how we did it, so I know a little about it:

VB Code:

Sub OpenDrawer()
  On Error GoTo ErrorOpenDrawer
  Open "//server/lpt" For Output As #1
    Print #1, Chr$(27) & Chr$(112) & Chr$(0) & Chr$(25) & Chr$(250)
  Close #1
  On Error GoTo 0
  Exit Sub
ErrorOpenDrawer:
  On Error GoTo 0
End Sub

and I know that it is VB. my point is that it also works in HyperTerminal

Hi all

Thanks for the input it is all brilliant, after chatting to the hardware technition guys, turns out that the connection that you plug the drawer into (i am told) has to be a specific type as you need to fire a 25v pulse down the cable to open the drawer.

On the till system we are using apparently there is a specific port that will do this and usually on receipt printers there is also a specific port to do it from...

So I am assuming this is he start of all my problems though Im still not convinved my .net code is working as I cant see any bytes moving to the com port. Will test more from the till hopefully today...

re: the .net code I am using the hPort value is the reference to the "file" as it were

Code:

---

hPort = CreateFile(portname, GENERIC_READ + GENERIC_WRITE, 0, 0, OPEN_EXISTING, 0, 0)

---

And the written value is used as a ref variable which holds the result of that function. ie. generally it comes back as 1 saying its written something (if you beleive it!!)

Will post when I find out more. But think I will end up writing a OCX in VB6 *vomit* :D

http://www.epanorama.net/circuits/parallel_output.html

http://www.a1vbcode.com/vbforums/shw...essageID=10184

And the best link I found:

http://www.codeproject.com/vb/net/Co...ade_simple.asp

dglienna, why on earth are u using Printer.EndDoc, in fact...why are you using the Printer object at all??? :confused:
That makes no sense what so ever :( Why are you using it?

Woka

Also, I know this isn't code, but it's a pre built solution for handling COM and Serial ports. It may be worth spending some cash...personally I wouldn't ;)

$300 ouch! :(

http://www.scientificcomponent.com/p...roller_net.htm

Woka

Thanks. I'll change it. It was an oversight. :sick:

I was ejecting a receipt at the same time that I opened the drawer.

And this...?

Quote:

---

Originally Posted by dglienna

VB Code:

Printer.Print Chr$(27) & "p" & "0"
Printer.EndDoc

---

I am not quite sure what the above will do. What makes you think this will access the com port for a till???

Woka

The printer/drawer is hooked up to the parallel port, and when the printer receives that sequence, it opens the drawer. It is a receipt printer.