ACC HDLC-NRM (SDLC) User's Guide

Chapter 3 37

Using HDLC-NRM (SDLC) Protocols

Status and Error Messages

Error and other conditions are reported to the a pplication program

through two kinds of status codes.

The defines for these status codes are located in zcomstatus.h and

zx25status.h.

Buffer Completion Statuses

Buffer completion statuses are generated by the protocol on all transmit

messages. Depending on t he mode parameter selected when using the

zsend call,theapplicationwillseeeithernotransmitresponsemessages,

error responses only, or all transmit response messages. The status code

in these messages indicate either the successful transmission of the

message, or the reason why it could not be transmitted.

The buffer completion statuses listed in the following table may be

generated by t he H DLC-NRM (SDLC) protocol.

Table 3-1 Buffer Completion Status

Status Code Value Description

IO_OK

(0)

No error detected.

This message was successfully transmitted to and

acknowledged (if appropriate) by the receiving station.

IO_DSBL

(1)

Terminal disabled.

Messages cannot be transmitted to a disabled terminal.

IO_TX_TMOUT

(2)

Cable or local modem fault.

This message cannot be sent or acknowledged because

a “transmit blockage” condition exists.

IO_BUSY

(3)

Terminal busy for too long.

Messages cannot be sent to the remote station because

it is busy.