Installation guide

40 DC 900-1564A

Synchronous Link Control (SLC) Programmer’s Guide

4.2.4 Control

DLI_PROT_CONTROL can be used only when SLC protocol service is configured. It is not

supported when SLC envelope service is conﬁgured.

An application reads a

DLI_PROT_CONTROL response when the ICP receives any link con-

trol block (LCB) that exerts stop/resume ﬂow control. An application exerts operator

control over SLC channel operation by writing a

DLI_PROT_CONTROL command to the

ICP.

The ICP maintains three local operational control ﬂags for each channel simulta-

neously. The

opr_channel_state ﬂag retains a value of SLC_OPR_CHANNEL_START (default)

or SLC_OPR_CHANNEL_STOP until a new value is requested. The opr_in_state ﬂag retains

a value of

SLC_OPR_IN_RESUME (default) or SLC_OPR_IN_STOP until a new value is

requested. The

opr_out_state ﬂag retains a value of SLC_OPR_OUT_RESUME (default) or

SLC_OPR_OUT_STOP until a new value is requested. The DLI_PROT_GET_STATUS_REPORT

command can be used to read the current values of these status ﬂags (Section 5.10 on

page 72). The header formats and operator control options are detailed in Section 5.4

on page 65.