The Virtual Serial Connection provides the signotec signature pad on the client as a virtual COM port. This COM port is mapped into the server session using built-in Citrix or RDP mechanisms, so that the application on the terminal server can address the pad like a local serial interface.
This variant can be used with Citrix Virtual Apps and Desktops as well as Microsoft RDP, and generally also works with other remote protocols, provided they support serial port mapping.
How It Works
The conversion of the USB device into a virtual COM port takes place on the client. signotec offers two approaches for this:
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Hardware-based conversion (
FT100variant) — devices whose item number ends inFT100contain an integrated USB-to-serial converter from FTDI. They present themselves directly to the client as a serial device. Only the standardized FTDI driver is required on the client. On Linux systems, this is included as a kernel module (ftdi_sio) in all common distributions; on Windows, it is usually downloaded automatically via Windows Update the first time the device is connected. -
Software-based conversion (
U100variant with signotec VCOM driver) — devices with a USB connection (item number ending inU100) can be provided as a virtual COM port on the client via the signotec virtual COM port driver (VCOM driver for short). The driver is available for Windows and Linux and must be licensed for a fee.
In both cases, the client sees the pad as a serial port. The COM port is then passed into the session via the Citrix or RDP mechanism; the server application addresses the pad through this port.
Requirements
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signotec signature pad
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PC or thin client running Windows or Linux
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Citrix Workspace App or Microsoft Remote Desktop Client
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For
U100: licensed signotec VCOM driver on the client -
For
FT100: standardized FTDI driver on the client (usually available without any action required — Linux: kernel module, Windows: via Windows Update) -
Administrative privileges on the client, if a driver installation is required
For centrally managed thin clients without access to Windows Update, it may be necessary to provide the FTDI driver via a custom partition or the image. The details depend on the thin client OS used and are outside the scope of this documentation.
Driver Installation
FTDI variant (FT100)
On most systems, no manual installation is required. If the FTDI driver is nevertheless not available automatically, it can be obtained directly from the manufacturer: https://ftdichip.com/drivers/.
VCOM variant (U100 with signotec VCOM driver)
The signotec VCOM driver is installed on the client with administrative privileges and requires a valid license. Available through signotec Sales. A demo version for testing the connection is available on request.
Configuration in Citrix
For the client's COM port to be available in the Citrix session, COM port redirection must be enabled in the Citrix policies. The relevant policies can be found in Citrix Studio under Policies → ICA → Port Redirection:
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Client COM port redirection policy — set to Allowed.
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Auto connect client COM ports policy — optionally set to Enabled so that the port connects automatically when the session starts.
After enabling the policies and restarting the session, the client's COM port is available in the server session. The COM port number used in the session may differ from the local numbering on the client and should be checked in the session's Device Manager or in the application.
Configuration in RDP
COM port redirection over RDP can be enabled in two ways:
Per connection via the Remote Desktop client
In the Remote Desktop client (mstsc.exe), check the box under Local Resources → Local devices and resources → More → Ports. This setting applies to the specific connection.
Centrally via Group Policy
On the terminal server, or centrally via GPO: set Computer Configuration → Administrative Templates → Windows Components → Remote Desktop Services → Remote Desktop Session Host → Device and Resource Redirection → Do not allow COM port redirection to Disabled.
After enabling redirection and reconnecting the session, the client's COM port is available in the server session.
Verification
After configuration, the connection can be tested with a signotec-compatible application in the remote session — for example signoSign/2 or a line-of-business application using the signoPAD API. The application must recognize the COM port assigned to the pad in the session.
In the Citrix or RDP session, redirected client COM ports appear in the session's Device Manager under Ports (COM & LPT). The numbering in the session may differ from the numbering on the client.
If you experience issues, check in this order: driver installation on the client (FTDI or VCOM), detection of the pad as a COM port on the client (Device Manager), the Citrix policy or RDP configuration for COM port redirection, and detection of the port in the server session.