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

Chapter 8 169
Intrinsics Reference
FCONTROL(10, 11)
FCONTROL(10, 11)
Parameters
controlcode 10 or 11 — Changes the line speed of a device.
param 16-bit unsigned integer by reference
(required)
Passes a value which specifies a new line speed.
Notes A controlcode value of 10 or 11 is used to
programmatically change the line speed associated
with a device. Both input and output speeds are
affected. The value passed in param must be expressed
in characters per second (1 character per second =
10 bits per second). The choices supported by MPE/iX
are 30, 120, 240, 480, 960, and 1920. For direct connect
devices on DTC 72MX, 3840 is also valid. These equate
to the MPE/iX supported speeds of 300, 1200, 2400,
4800, 9600,19200, and 38400 bits per second. Any other
settings will cause the intrinsic to return a condition
code of CCL.
The controlcode values of 10 and 11 function in an
identical manner and can be used interchangeably. The
duplication exists because early versions of the
HP 3000 (Series II/III) supported a terminal controller
(the ATC), which allowed different speeds to be used for
input and output on the same device. For devices
attached to the ATC controller a controlcode of 10
adjusted the input speed while a controlcode of 11
adjusted the output speed. Split speeds for input and
output are not supported on MPE/iX.
You must be sure the speed associated with a device
matches the physical speed setting of the device and of
the modem if a modem is part of the connection. If you
programmatically change the speed of a device, your
program should request that the speed setting be
manually changed at the device as well.
If either of these FCONTROL calls is issued against a
terminal connected via PAD, DTC Telnet, Telnet/iX, or
VT, the call will return a CCE condition code but will
actually have no effect on the speed at which the device
is transmitting. Additionally, the call will return a
meaningless value in param.