Appendix B: Scanning Troubleshooting
This content applies to ScrewDrivers Pro and Enterprise editions.
When you're troubleshooting ScrewDrivers Scanning, you'll find that most issues relate to TWAIN Data Source configuration, Windows profile handling, or scanner-specific timing problems. This reference provides answers to frequently asked questions and systematic approaches to the most common scanning problems you'll encounter in remote session environments.
Overview
The troubleshooting process for ScrewDrivers Scanning involves three key functional areas: the application being used to acquire the scan, the ScrewDrivers Scanning Session Agent and client, and the ScrewDrivers Scanning DS (Data Source). The most common issues you'll face include scanner detection problems, TWAIN configuration conflicts, and timeout errors with slower scanners.
As with any troubleshooting effort, the recommended approach eliminates possible causes systematically before focusing on the root cause. Start by testing the ScrewDrivers Scanning Session Agent with multiple clients. If you see the same negative results across multiple clients, the problem likely resides on the server. After you've isolated whether the issue is server-side or client-side, you can focus your troubleshooting efforts on the specific component causing the problem.
General Troubleshooting Strategy
Before diving into specific issues, test the ScrewDrivers Session Agent with multiple clients to determine if the problem is consistent. If the same negative results occur across multiple clients, the issue almost certainly resides on the server rather than individual client workstations. Once you've isolated the problem to either the server or client, review the specific troubleshooting recommendations in the sections below.
If you can't resolve the issue using these recommendations, contact support@tricerat.com for additional assistance. Support will need the detailed information you've gathered during your troubleshooting process, including which clients you tested and what results you observed.
TWAIN Data Source Configuration
The TWAIN Data Source (DS) configuration is central to scanning functionality. Understanding how TWAIN DSs work and where they're located will help you resolve many common scanning issues.
Required TWAIN Data Sources
The only DS required on the server is the ScrewDrivers Scanning DS, which is loaded during ScrewDrivers Scanning installation. You don't need any software from the scanner manufacturer on the server. If you've been testing USB redirection or other solutions, you might want to consider removing any other scanner software already loaded on the server. By removing these extra DSs, your users have fewer choices when selecting a DS because the ScrewDrivers Session Agent DS will be the only one listed.
Locating TWAIN Data Sources
You can determine what TWAIN Data Sources are currently loaded by checking specific Windows directories. 32-bit TWAIN DSs are located in folders under C:\Windows\twain_32, while 64-bit TWAIN DSs are located in folders under C:\Windows\twain_64. Each folder contains a file with a .ds extension—this file is the DS, which is actually a DLL. Other files might also be located in the folder. ScrewDrivers Scanning installs both a 32-bit DS and a 64-bit DS.
Removing TWAIN Data Sources
If the scanner manufacturer has an entry in Control Panel under Programs and Features, Tricerat recommends using that method to uninstall the DS. If the scanner manufacturer doesn't have an entry in Control Panel, you can delete the appropriate folder under C:\Windows\twain_32 or C:\Windows\twain_64. Note that similar folders might exist under each user's profile at %USERPROFILE%\Windows\twain_32 or %USERPROFILE%\Windows\twain_64.
Windows Image Acquisition Support
ScrewDrivers Scanning installs a single TWAIN DS on the server. The built-in utilities from Microsoft support only Microsoft's Windows Image Acquisition (WIA) drivers. If you're using WIA drivers instead of TWAIN drivers, you'll need to work within the constraints of Microsoft's WIA architecture.
Windows User Profile Considerations
TWAIN's interaction with Windows user profiles can cause confusion in remote session environments. Understanding how TWAIN uses profile folders will help you avoid common configuration problems.
User Profile Folder Usage
Some applications use the C:\Windows folder and some use the %USERPROFILE%\Windows folder. Tricerat supplies a batch file that should run after each user login: C:\Program Files\Tricerat\ScrewDrivers\Scanning\UserCopyScanectDS.bat. This batch file copies the ScrewDrivers Scanning DS to the user's profile folder, ensuring that the DS is available regardless of which folder path the application uses.
Mandatory Profile Compatibility
ScrewDrivers Scanning is compatible with mandatory profiles, but you must ensure that the mandatory profile contains the files that the UserCopyScanectDS.bat script sets up. After being copied into the user's mandatory profile, these files don't change from session to session. However, if you update the ScrewDrivers Scanning version, you must remember to also update these files in the mandatory profile template.
Scanner Timeout Configuration
Some scanners operate more slowly than others, and some users receive timeout message dialogs during scanning operations. You can adjust the timeout value to accommodate slower scanners.
To edit the timeout value, open Registry Editor (regedit) on the ScrewDrivers server and navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Tricerat\ScrewDrivers\Scanning. Add a DWORD value named ClientWait and set the value to milliseconds, making sure to select decimal as the input format. The default is 30000, which represents 30 seconds. To double the wait time, use a value of 60000. Exit Registry Editor when finished.
The next time a user starts their TWAIN-enabled application, this updated setting takes effect. The user doesn't have to log out and back in—the new timeout applies immediately to new scanning sessions.
Default Scanner Configuration
You can control which scanner is automatically set as the default scanner for a remote session through the ScrewDrivers Scanning Client application. Open the ScrewDrivers Scanning Client application and open the Scanners tab. The tab displays all the scanner drivers, by name, that were detected on your client or client's network that can be brought into your session. The first scanner displayed in the list of available scanners is always set to the default scanner for your session.
To set another scanner as the default scanner, drag the selected scanner to the first position in the list. The scanner at the top of the list will be the default for all future sessions until you change this configuration.
Citrix Plugin Registration
If you're using ScrewDrivers Scanning with Citrix and experiencing issues, you might need to register the Citrix Plugin for all users. Open the ScrewDrivers Scanning Client application As Administrator, then open the About tab. Under "Register Citrix Plugin," select "For all users" and click Register. This ensures that the plugin is available regardless of which user account is logged in.
TWAIN Redirection Conflicts
If you've been testing TWAIN redirection in your Citrix environment before implementing ScrewDrivers Scanning, you must disable the TWAIN redirection Windows policies before ScrewDrivers Scanning can work. If you don't disable these policies, you cannot see the ScrewDrivers Scanning DS on the server—you can only see the data sources that are loaded on your client. Check your Citrix policies and disable TWAIN redirection to allow ScrewDrivers Scanning to function properly.
Scanner Driver Requirements
ScrewDrivers Scanning doesn't require any special software to be installed from the scanner manufacturer. Only the TWAIN driver or the WIA driver must be installed on the client workstation. Use the Test Scanners function to validate that the driver is operating correctly before attempting to use it in production.
TWAIN vs. WIA Drivers
If your scanner manufacturer installed both a TWAIN driver and a WIA driver, Tricerat generally suggests starting with the TWAIN driver and running some scanning tests. If the tests reveal any issues, try using the WIA driver to see if the issues persist. If problems continue with both driver types, check the manufacturer's website for an updated driver.
The installation CD provided with a scanner often doesn't contain the latest driver version. Tricerat recommends checking the manufacturer's website to confirm you're using the most current driver. You should also check for any firmware updates that might be available for your scanner, as firmware updates can resolve compatibility issues and improve performance.
Session Agent Troubleshooting
The troubleshooting approaches in this section focus on server-side issues that typically affect multiple users rather than individual workstations. When you're experiencing scanning problems that affect multiple users, start your troubleshooting with these Session Agent-focused procedures.
The key to effective Session Agent troubleshooting is systematic testing with multiple clients. If the same problem occurs across different client workstations, you can be confident the issue resides on the server. Once you've confirmed a server-side issue, review the TWAIN Data Source configuration, Windows profile handling, and timeout settings described in the sections above.
Client Troubleshooting
When scanning problems affect only specific users or workstations, focus your troubleshooting on client-side configuration. The most common client-side issues involve scanner driver configuration, TWAIN vs. WIA driver selection, and Citrix Plugin registration.
Start by verifying that the scanner driver is properly installed and working on the client workstation. Use the Test Scanners function to validate driver operation. If the test fails, the problem is with the client-side scanner driver rather than ScrewDrivers Scanning. If the test succeeds but scanning still fails in remote sessions, check the Citrix Plugin registration and TWAIN redirection policy settings.
Related Resources
- How-To Guide: See the scanning configuration guides in the How-To Guides section for detailed setup procedures
- Explanation: See the scanning capabilities explanation for conceptual information about TWAIN architecture
- Troubleshooting: See the main troubleshooting section for additional diagnostic approaches