Asynchronous Serial Communications Programmer's Reference Manual (32022-90052)

Chapter 8 213
Intrinsics Reference
FDEVICECONTROL
MPE V or HP-UX local client, the subsystem break
character must be set to the existing subsystem break
character when enabling transparent mode.
26 Device XON/XOFF enable.
This directive enables and disables XON/XOFF flow
control between the device and the DTC. A buffer
value of 1 enables device XON/XOFF, and a value of 0
disables XON/XOFF. When device XON/XOFF is
enabled, the DTC stops sending data to the device
when it receives XOFF and resumes when it receives
XON. The DTC does not send XON/XOFF characters to
the host. When device XON/XOFF is disabled, the XON
and XOFF characters are passed to the host as data.
When XON/XOFF flow control is disabled, data
overruns can occur.
If this control is issued to a terminal connected via
PAD, DTC Telnet, Telnet/iX or VT, it will return a CCE
condition code, but no terminal control action will occur.
27 Set XOFF timer value.
This directive enables or disables the XOFF timer<.
The timer is enabled by passing a positive value,
representing a time limit in seconds, in the buffer
parameter. When enabled, the XOFF timer causes a
warning message to be sent to the console if a device is
XOFFed for a time exceeding the set limit. A buffer
value less than or equal to 0 disables the XOFF timer.
If this control is issued to a terminal connected via
PAD, DTC Telnet, Telnet/iX or VT, it will return a CCE
condition code, but no terminal control action will occur.
28 Block mode types supported.
This directive returns a value indicating the type of
block mode supported by the driver. The possible return
values are shown below:
7 = both line and DTC style page block
mode
15 = PAD terminal supporting page block
mode
This directive is not supported for terminals connected
via DTC Telnet or via VT from a PC or HP-UX local
client.