Serial Connection Requirements for the Windows NT Driver (v3.1c)
This article details the standard serial connection and hardware handshaking requirements for the legacy Windows NT v3.10c touch driver from Elo — Now part of Zebra Technologies.
Standard Serial Connection Requirements
The Windows NT v3.10c driver normally requires the following serial connections to be active and properly communicating:
- Touchscreen coordinate data is sent on the Receive Data (Rd) line, and a Ground (Gnd) connection is always required as a reference.
- The Data Set Ready (DSR) signal is used to indicate to the computer that the touch controller has power.
- The Clear to Send (CTS) signal is used to indicate to the computer that the controller has successfully passed its Power-On Self-Test (POST).
- The POST results are requested by the computer when the driver sends a command on the Transmit Data (Td) line.
Driver Failure Conditions: The driver will load, but the touchscreen will not function under ANY of the following conditions:
- The POST results are not successfully received by the computer.
- Controller power is not indicated (i.e., the DSR signal is not high).
- POST completion is not indicated (i.e., the CTS signal is not high).
Troubleshooting Connection Issues
If a wire in the serial cable is broken, or if you are using a simplified two-wire connection (Rd and Gnd only), it will be necessary to disable the POST results check. This is commonly referred to as "disabling handshaking." To learn how to do this, please see our guide on Disabling Hardware Handshaking.
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