Envoy Application Programming Manual

Envoy Application Programming Manual—427159-001
10-1
10
Asynchronous Line Supervisor Protocol
The asynchronous line supervisor protocol is a general-purpose asynchronous line-
handler. It provides a straight-through connection to the communications line, with the
user application performing all line-control and protocol functions. You can use this
protocol to connect devices that support non-standard asynchronous interfaces. In
general, this protocol is used for the following implementations:
•
Supervisor station for a network of asynchronous terminals
•
A receive-only port on a read-only line
Topics discussed in this section include:
•
Protocol Capabilities on page 10-2
•
End of Text Character on page 10-2
•
Termination and Strip Characters on page 10-2
•
Read-Only Mode on page 10-3
•
Application Process Interface on page 10-4
•
File-System Procedures on page 10-8
•
Message Formats on page 10-11
•
File-System Errors on page 10-12
•
Line Action by Procedure Call on page 10-13
•
Line-Error Handling on page 10-20
•
Read-Only Programming Examples on page 10-23
•
Asynchronous Supervisor Programming Example on page 10-25
Note. The asynchronous supervisor protocol is specified by a single subtype (40). This sub-
type has two possible profiles, PENVASC and PENVSIM. When you specify a particular pro-
file, Envoy automatically sets up certain defaults. The defaults that accompany the PENVSIM
profile are intended to be used for a read-only line.