NS Basic/Palm provides support for Symbol devices starting with version 2.0. The necessary libraries and samples are installed along with NS Basic/Palm: there are no extra files to download.

The Symbol routines work on all Palm OS devices from Symbol, as well as the Symbol Springboard for Visor. Please note that there are a few wrinkles with the Visor version: they are documented further on in this document. If you have a Symbol SPT15xx, it's a good idea to flash Palm OS 3.5 to the device. With older ROM versions, there is a potential error when using the STOP statement.

The routines are very simple to add into a program. Check out the sample called "Symbol" to see how it is done.

The Easy Way

1. In your startup code, include the line

LoadLibrary "NSBSymbolLib"

This lets NSBasic know that you will be using the library.

2. Somewhere in the initialization, possibly in the After code of your main form, call the function

NSBSymbolLib.IsPalmSymbolUnit()

This will return 1 if the program is running on a Symbol unit and 0 otherwise. If it returns 0, do not try to use any further Symbol functions.

3. In the Events code of your main form, when you receive an event type 34815, call this string function to get the scanned value:

scannedData = NSBSymbolLib.GetLastScanData()

The Events code will be called whenever the user pushes the yellow Scan button on the Symbol device. NSBSymbolLib.GetLastScanData() returns a string giving the last barcode scanned. Do whatever is appropriate with this bar code.

4. Compile your NSBasic program and download it plus the NSBSymbolLib.prc directory to your Symbol device. Your program should behave appropriately according to the last settings of the scanner.

The Symbol.prj sample does this. It also gets the bar code type using the integer function NSBSymbolLib.GetBarType().

The Harder Way

1. Events

You can display a dialog box when you recieve event 34816. Event 34817 can normally be ignored, as you will get an event 34815 after a second or two anyway. If no bar code was successfully scanned, NSBSymbolLib.GetLastScanData() returns "NR" and NSBSymbolLib.GetBarType() returns 0.

2. Functions

3. Barcode Types

1. Event codes differ on the CSM150 compared to the SPTxxxx

  Use -30721 instead of 34815
  Use -30720 instead of 34816
  Use -30719 instead of 34817

2. Avoid making library calls in the project startup and termination

During project startup and termination, the normal program "event loop" processing is not performed. While it may seem natural to perform some library calls such as CmdScanEnable in the startup code after the LoadLibrary, in practice is causes events to get queued but not processed and a fatal error results.

If it is necessary to perform a Symbol library call in the project startup or termination, immediately follow the call with the following code:

  Dim EventType as Variant
  SysTrapSub 285, 2, EventType, 1	'EvtGetEvent
  SysTrapSub 169, 1, EventType		'SysHandleEvent

The ScanConfig Utility

ScanConfig is run by using AppLaunch() from within your NSB/Palm program, and supplying both a cmd integer to designate the attribute to be changed plus a data string with the associated desired value(s).

The critical code is slightly different than in the Symbol: here is how it looks:

Startup Code:

   LoadLibrary "NSBSymbolLib.inf", "NSBSymbolLib"
   NSBSymbolLib.cmdScanEnable()

Form Event Code

   Dim foo as String
   Dim bar as Integer
   
   If sysInfo(9)=8459 Then 'Janam Scan Button hit
	   foo = NSBSymbolLib.GetLastScanData()
	   fldBarCode.Text = foo  
	   bar = NSBSymbolLib.GetBarType()
	   fldCodeType.Text = str(bar)
   End If

Working with an Aceeca Ltd. ID::Verifi PDA API for Scanned Data
Contributed by Michael Assia SY-CON Systems, Inc.

We found the Aceeca Palm 4.1-based PDA to be an alternative to the Symbol SPT series units. Included from Aceeca is a very capable "wedge" scanner program to make entering barcoded data into any application an easy matter. Why then would you need anything else for your application?

The Aceeca wedge software reads a barcode and completes the current field where focus remains on the field. This occurs for any input field regardless of how the data is entered including the Symbol SPT series with the NSBSymbolLib. The user must tap into the next field before entering or scanning the next value. It was our desire, however, to make barcode input an intuitive process with little to no tapping, just scan to complete the field and automatically move to the next input field ready for the next scan. You may also want to perform a different operation or display messages based on the data obtained from the scan immediately after it is received. You can also get the desired results using the Aceeca wedge API by intercepting the events and characters generated by the software as it decodes the barcode characters read.

The behavior of the Aceeca API within an NSBasic written application differs from that described in the BCS2 write-up and C/C++ example. Within an NSBasic application you will need to use the GetEvent call from the NSSystemLib to detect the KeyDown event (4) that occurs for each character scanned. The GetEvent must be called in the form's Event code to handle this process. The actual decoded character is obtained by calling another NSSystemLib function, KeyEventChr.

The Aceeca API continues to generate the KeyDown event for each character it decodes until the barcode is fully decoded. However programmatically there is no way to know how many characters are to be received. To signify the end of a barcode string, you will need to use the Advanced setup for the Aceeca wedge software on the PDA and add a CR LF (carriage return & line feed) or some other special characters (2) to the end of the character string representing the barcode data read. Make sure the characters you choose are not found in any barcode symbology you are using.

Project Startup

' Define several key fields so their value exists thorough out the program
'
Global dataread as String         'to hold scanned characters until all are received
Global Cr as String	   
Global Lf as String
.
.
	Cr = Chr(13)
	Lf = Chr(10)
	LoadLibrary "NSBSystemLib", "NSL"	

Sub Form1047_Event()
Dim evnt as Integer
'
    evnt = NSL.GetEvent(500,0,0)
    If evnt <> 4 Then Exit Sub
'
'   Event was keydown from Aceeca PDA
'   Get each character one-by-one read by scanner 
'
    keychr = NSL.KeyEventChr()
    If chr(keychr) <> Cr And chr(keychr) <> Lf Then 
       dataread = dataread + Chr(keychr)
       Else
       If chr(keychr) = Lf Then Exit Sub
'
' After getting Cr, put string into appropriate input field.
' 
       Select Case statecode
             Case 1
                statecode = 2
                in1.text = dataread
                In2.Setfocus
                in2.text = ""
            Case 2
                statecode = 3
                in2.text = dataread
                In3.Setfocus
                in3.text = ""
            Case 3
                in3.text = dataread
                statecode = 4
                In4.SetFocus
                in4.text = ""
            Case 4
                in4.text = dataread
                statecode = 1
                in1.SetFocus
                in1.text = ""
            Case Else
            End Select 
            dataread = "" 
    End If             
End Sub

In my opinion the 3E model is junk -- it is a CMOS scanner with a very slow processing speed and horrid success rate. Nearly unusable in my book.

But I do use the 3M model now -- it is a class 1 laser and works pretty well. Not quite as nice as the Symbol scanners, but WAY better than the 3E and still quite a bit better than the various Grabba models.