## Input/Output Device Driver Reference

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### DTR Control Mode

The control modes for DTR are:

Enable
Disable
Input Handshaking

The Enable and Disable control modes of DTR affect DTR processing during a First Level Open. When these control modes are set through the ASYNC_ SETDCBINFO, the value of the DTR signal can be modified immediately by the physical device driver. The action depends on the previous control mode of DTR and the current value of the DTR modem control signal. If the control mode of DTR is Input Handshaking, then the device driver controls the DTR signal, depending on how full the receive queue is. The bits that control these states of the device driver are in the device control block.

Initial Value Enable
First Level Open No effect
Mode Utility User interface to change the DTR Control Mode of the physical device driver