Company: Link Technologies
Case No: L12597. Project: 13.10: LinkSOFT version 13.10 - Improvements and Stabilisation
Logged By: Vineet (Link Business Solutions) on behalf of Sanjay (Link Technologies) on 29 Sep 2021 03:49PM
Priority: High
Product: Point of Sale
Group: Change Request
Time Taken: 19.00 (Weight: 20.00)
Version: 13.10.1011
Assigned To: Sanjay (Link Technologies)
Circulation: Development, Sanjay, Vineet
Resolve By: Sunday, 10 October 2021 11:59 PM [932 days since logged date]
Status: Closed
Subject: Error Message in POS When User Logs Off when Customer Display is Enabled using COMM Port
Section A - Describe what the issue is about. Include Error Message (Include screenshots) 

When the Customer display is enabled, the below error message pops up when the user logs off POS.

Figure 1.1 Error Message from POS

"Image has been removed to reduce document size."

Table 1: Environment Details where this issue can be seen

Server Name:


Database name:


Application Hosted on:

Login User ID/Password:


Client Operating System:


LinkSOFT Version:


Section B. 
Relevant History Information: Any information that is relevant to this issue, or may have caused this issue.

Section C. The issue can be reproduced by performing the following steps: ?
  1. Enable Customer Display.
  2. Select your COMM Port. In some PC's COMM7 is used and in some COMM8.
  3. Set Display Model as "Other"
  4. Set Customer Display Line 1 as "Dannys Pte Limited"
  5. Set Customer Display Line 2 as User
  6. Login to POS. Note customer display loads successfully
  7. Scan and sell items, display works fine.
  8. Now click on Log Off. Error message as "The parameter is incorrect ." comes up

Figure 1.2 Snap of Setup at Site

"Image has been removed to reduce document size."
Audit Notes:Edited by sanjay on 18/10/21 15:50. Edited by sanjay on 07/10/21 14:02. Edited by sanjay on 07/10/21 13:54. Edited by sanjay on 07/10/21 13:50. Edited by sanjay on 06/10/21 15:49. Edited by sanjay on 06/10/21 10:34. Edited by sanjay on 06/10/21 10:34. Edited by vineet on 04/10/21 17:11. 
29 Sep 202103:50PM Comment 1 by Sanjay (Link Technologies) Case L12597 added to project 13.04
06 Oct 202110:33AM Comment 2 by Sanjay (Link Technologies) Assigned To: Vineet (Link Business Solutions) Followup Date: 10-10-2021 03:59 PM Time Taken: 4.00 Notes: ETC extended from: 30/09/2021 to 10/10/2021

Hi Vineet, I am unable to reproduce the issue with the instructions you have sent.

I checked all the code and there is a check for validity of Port numbers so I cannot see where this issue can occur unless I can reproduce it.

Did you set this up using QA8? if so, please update the case with steps so I can reproduce the issue.

06 Oct 202110:34AM Comment 3 by Sanjay (Link Technologies) Case L12597 removed from project 13.10
06 Oct 202103:49PM Comment 4 by Sanjay (Link Technologies) Case L12597 added to project 13.10
06 Oct 202104:09PM Comment 5 by Sanjay (Link Technologies) Assigned To: Sanjay (Link Technologies) Followup Date: 06-10-2021 07:49 PM Time Taken: 4.00

On-site teams session with Vineet and Sanjay to run some diagnostics. Notes below:

  1. There are two error messages being logged:
    1. Path Error for Customer display - This was corrected by removing the Display Number as the customer does not have a LCD display to show Images
    2. Serial Port error (see figure 1 below). THis error is preventuing the user from exiting from the POS Main screen
  2. The unit is a POSIFLEX POS station with a built in USB/Serial port emulator

Figure 1 - Serial Port Error

Message: The parameter is incorrect.
BaseException: System.IO.IOException: The parameter is incorrect.
at System.IO.Ports.InternalResources.WinIOError(Int32 errorCode, String str)
at System.IO.Ports.InternalResources.WinIOError()
at System.IO.Ports.SerialStream.InitializeDCB(Int32 baudRate, Parity parity, Int32 dataBits, StopBits stopBits, Boolean discardNull)
at System.IO.Ports.SerialStream..ctor(String portName, Int32 baudRate, Parity parity, Int32 dataBits, StopBits stopBits, Int32 readTimeout,
Int32 writeTimeout, Handshake handshake, Boolean dtrEnable, Boolean rtsEnable, Boolean discardNull, Byte parityReplace) at System.IO.Ports.SerialPort.Open()
at LBS.LINKPOS.UI.POSMain.UpdateDisplay(String DisplayText)


Since we do not have a Serial Port display to test this on, we will suppress the user messages and log them for now as this is preventing users from logging of the POS form.

Next step:

  1. Test this on site with Vineet

07 Oct 202110:06AM Comment 6 by Sanjay (Link Technologies) Assigned To: Sanjay (Link Technologies) Followup Date: 07-10-2021 01:49 PM Time Taken: 4.00

I have made changes to the logging of serial port operations to achieve the following:

  1. Log error in more detail so we can determine the cause of the issue
  2. Allow the user to log out even if there is a failure in the serial port closure

The update is in 13.10. I need a way to test this. Will check with LBS to see if this can be done on-site on a test machine.

07 Oct 202101:50PM Comment 7 by Sanjay (Link Technologies) Assigned To: Development Followup Date: 07-10-2021 05:48 PM Time Taken: 5.00
PART A - Development work for this case has been completed.

1. The change will be available in version:13.10

2. The following changes were made(Include Database object names, Program classes, and any other relevant information):

  1. Removed User Alert for Serial Port Operations
  2. Added logging for serial port transmissions
  3. Added detailed logging on serial port issues for diagnostics

3. Affected Areas:

  1. POS - Writing data to serial Port Display

4. The issue was caused by:

  1. Unnecessary User alerts

5. Other Relevant Notes
6. Next Step
(Review and System Test (Developer) -> UAT (Quality) -> Documentation): UAT

07 Oct 202101:53PM Comment 8 by Sanjay (Link Technologies) Assigned To: Sanjay (Link Technologies) Followup Date: 07-10-2021 05:50 PM Time Taken: 2.00
The following tests were performed:

Table 1 - Test Results
#Test Case DetailsPass/FailComments
 1Configure serial port display to COM 1 and write data
 2Force failure on COM1
No user notification. The error log contains exception JSON
 3Configure Unavailable Port
Log message shows invalid Port
 4User notification
User is not notified with popup User can log off.

Environment Details

  1. OS version: Win10
  2. Application version: 13.10
  3. Setup on:
    1. Server: LinkQA4
    2. Database: LinkSOFT
    3. LinkSOFT URL: HTTP://
  4. Login Details: Standard username and password for user "admin"

Next Step: Closure

07 Oct 202101:54PM Comment 9 by Sanjay (Link Technologies) ETC was changed from 10/10/2021 to 10/10/2021
If you have any queries regarding this support incident, please email and include the Case No: L12597 in the subject line of all emails regarding this issue.

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