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-side session using the native tools of the Citrix or RDP session, so that the application on the terminal server can address the pad as if it were 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 the mapping of serial ports.
How it works
The conversion of the USB device into a virtual COM port takes place on the client. signotec offers two paths for this:
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Hardware-side conversion (
FT100variant) — devices whose article number ends withFT100contain an integrated USB-to-serial converter from FTDI. They register on the client directly as a serial device. Only the standard FTDI driver is required on the client. On Linux systems this is part of all common distributions as a kernel module (ftdi_sio); on Windows it is usually installed automatically via Windows Update the first time the pad is connected. -
Software-side conversion (
U100variant with the signotec VCOM driver) — devices with a USB connection (article 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 connection. The COM port is then passed into the session via the Citrix or RDP mechanism; the server-side application addresses the pad through this port.
Prerequisites
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signotec signature pad
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PC or thin client with 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: standard FTDI driver on the client (generally available without any action — Linux: kernel module, Windows: via Windows Update) -
Administrative privileges on the client, if driver installation is required
For centrally managed thin clients without a connection to Windows Update, it may be necessary to provide the FTDI driver via a custom partition or through the image. The details depend on the thin client OS in use and are not part 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 the signotec VCOM driver)
The signotec VCOM driver is installed on the client with administrative privileges and requires a valid license. Available via signotec Sales. A demo version for testing the connection is available on request.
Citrix configuration
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 are located in Citrix Studio under Policies → ICA → Port Redirection:
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Client COM port redirection (German: Client-COM-Port-Umleitung) — set to Allowed.
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Auto connect client COM ports (German: Automatische Verbindung mit Client-COM-Ports) — optionally set to Enabled so that the port is connected automatically when the session starts.
After the policies have been enabled and the session restarted, the client's COM port is available in the server session. Which COM port number is used in the session may differ from the local numbering on the client and should be checked in the Device Manager of the session or in the application.
RDP configuration
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) under Local Resources → Local devices and resources → More → Ports, select the checkbox. The setting applies to the respective 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 the redirection has been enabled and the session reconnected, 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 with signoSign/2 or a line-of-business application using the signoPAD-API. The application must detect the COM port that is assigned to the pad in the session.
In the Citrix or RDP session, forwarded 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.
In case of problems, check in the following order: driver installation on the client (FTDI or VCOM), detection of the pad as a COM port on the client (Device Manager), Citrix policy or RDP configuration for COM port redirection, detection of the port in the server session.