User`s guide

DC 900-1317J 31
Chapter
2
ADCCP NRM Protocol
Summary
Protogate’s ADCCP NRM interface product is based on the American National Stan-
dard for Advanced Data Communication Control Procedures (ADCCP), which is a
standard protocol (ANSI X3.66-1979) that helps computers exchange information.
ADCCP defines link-level operation in several distinctly different configurations and
operating modes. ADCCP also supports eleven optional features that modify link-level
operation.
The following discussion refers to the normal response mode (NRM), asynchronous
response mode (ARM), and asynchronous balanced mode (ABM) of ADCCP opera-
tion. Note, however, that the communications package you have purchased supports
NRM only. ADCCP option 10 may be used to convert to an extended mode (NRME)
that allows longer delays between data transmission and data acknowledgment on the
link.
This chapter describes the ADCCP protocol in general (including features that may not
be supported in your package) and defines the normal environment in which ADCCP
is used. This information is provided solely for your interest and is not required for use
of this communications package.
2.1 Unbalanced Configurations
Some applications require a primary station to control and exchange information with
one or more secondary stations on a single data link. ADCCP achieves this by defining
a set of procedures for unbalanced mode operation.