Rockwell Automation 1771-KA2 Communication Adapter Module - Manual (Page 88)

Command Initiation, Execution, and
Monitoring
Chapter 7
7-16
Timeout preset monitoring is intended as a backup for the other
communication monitoring functions of the module. It is designed to
signal any condition where the module has not completed its
communication with another station or detected some fault condition
within a short time. Because this timer is primarily intended as a backup
for some LOCAL FAULT type of situation, its preset value is not critical.
In the examples in this manual, a nominal value of 5 seconds, coded 015,
is programmed as the timeout preset value. This value is appropriate for
most applications.
Programming the Preset Code
The timeout preset code for Data Highway communication is entered in
the header rung of the communication zone of program. The address field
of the third GET instructions in this rung is used for the timeout preset
code. Figure 7.8 shows the position of this rung element.
The 3-digit address of a GET instruction is an octal (base 8) number.
Because only octal values can be entered in this address field the timeout
preset value is a code, computed as outlined in this section.
As section titled “Timeout Preset Value” points out, the timeout preset is
not a critical value. For most applications, a 5-second present is
acceptable. The code for this timeout preset is 015. However, there may
be instance where another timeout preset interval is desired. Table 7.B
lists the 3-digit codes for intervals from 1 to 10 seconds. Note that values
listed provide nominal values that will vary with activity level in the KA2.
Table 7.B
Timeout Preset Codes
Timeout Interval
(Sec,) Code
1 011
2 012
3 013
4 014
5 015
6 016
7 017
8 020
9 021
10 022