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

188 Chapter8

Intrinsics Reference

FCONTROL(28, 29)

Some additional considerations apply when

transmitting data in block mode. The terminal must be

conﬁgured to perform in a manner compatible with the

expectations of the system and the application

requesting the block mode transfers. You should pay

particular attention to how Line/Page(D),

InhHndShk(G) and Inh DC2(H) are set when

conﬁguring a terminal for block mode processing.

Block mode processing is not supported with terminal

type 18.

User block mode is not supported on terminals

connected through DTC Telnet, Telnet/iX (from an

HP-UX Telnet client) or VT (from an HP-UX local client

(VT3K)). If posted to a device connected via DTC

Telnet, these calls will return a CCE condition code, but

no device control action will occur.

NOTE

Data overruns may occur during block mode transfers. Your program

must check for successful completion of each read operation and retry

as required. Use of timers during block mode reads is strongly

encouraged, since a data overrun occurring when the last character is

read would otherwise cause the port to “hang”. The standard block

mode read timer does not operate when user block mode protocol is

enabled.

Condition Codes

CCE Request granted.

CCG Not returned by this intrinsic.

CCL Failed because the ﬁle number speciﬁed did not belong

to this process or the device is not a terminal.

Additional Discussion

See the reference manuals for the terminals connected to your system.