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

Chapter 8 179

Intrinsics Reference

FCONTROL(23, 24)

Parameters

controlcode 23 — Disables parity generation and checking.

24 — Enables parity generation and checking.

param 16-bit unsigned integer by reference

(required)

This parameter has no meaning for these controlcode

values. Enter a dummy value of 0 to satisfy the internal

requirements of the intrinsic.

Notes A call to FCONTROL with a controlcode value of 23

or 24 determines whether or not parity is generated

and checked for data transmitted between the system

and a terminal. Use 23 to disable parity, 24 to enable

parity. FCONTROL(23) and (24) do not apply to

printers.

Parity can be used for terminals opened

programmatically as well as for those operating in

session mode.The default for both session and

programmatic devices is to not generate or check parity,

but to operate in 8-bit pass-through mode.

When parity is enabled, the Asynchronous Serial

Communications software (ASC) generates parity on

outgoing data and checks for parity errors on incoming

data. After the parity is checked, the parity bit is

always set to zero because the program using the data

has no need for parity information. Parity checking is

handled the same way in block mode as in character

mode.

The type of parity that will be used if parity is enabled

can be modiﬁed through a call to FCONTROL(36). If

FCONTROL(23) is used to disable parity after it was

previously enabled, a subsequent call to

FCONTROL(24) will reenable the same type of parity,

unless it was changed through another call to

FCONTROL(36).