Memory Access Rungs - Allen-Bradley 1771-KA2 User Manual

Chapter 5
Communication Zone Rungs
Local
Station
Number

Memory Access Rungs

5-4
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Figure 5.2
Header Rung
Address of
Timeout
Error Code
Preset
Storage Word
Code
011
077 015
[ G ]
[ G ] [ G ]
000
000 000
The 3 GET instructions in the header rung list the following:
Local station number
Address of ERROR CODE storage word
Timeout preset code
The local station number is a 3-digit number switch-selected on the
1771-KA2 module. This is an octal number from 010
110 to 376 .
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The ERROR CODE storage word is a status word in the data table of the
local station processor, controlled by the communication adapter.
(Section titled "Error Code Storage Word," chapter 6, describes the
significance of the ERROR CODE storage word.)
The timeout preset code gives a programmed timeout interval for
command completion. Based on the 3-digit value entered in the address
field of this GET instruction, the communication adapter module monitors
command execution for all commands sent from a station. In the
examples in this publication, the number 015 is entered as the timeout
preset code. This value, which designates a 5-second timeout preset, is
suitable for most applications. The significance of this preset code, its
computation, and timeout considerations are described in section titled
"Timeout Preset Value," chapter7.
The memory access rung defines data table words that you can access
with the following commands:
Protect write
Protect bit write
Protected commands, received from a remote station, may control only
those local station processor memory areas listed in memory access rungs.
02707
( L )
OFF
to 077 or from
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