Safe State Values (Configuration Words 20 Through 22); Communicating Real Time/Non-Real Time Information - Allen-Bradley 1734-VHSC5 User Manual

Communicating Real Time/
Non-real Time Information

Safe State Values (Configuration Words 20 through 22)

When either the host transitions to PROGRAM mode or a
communication fault (i.e. broken network cable) occurs, the module
copies these safe state words (counter control, output control, and
PWM value) into its real-time working buffer. The definitions are
identical to those described under Real-time Output Data with the
following exception: entering a PWM Safe State value outside of the
range, 0-9500, will result in a Hold Last State to be executed.
The Very High Speed Counter Module uses several words to
communicate real time input and output data as well as non-real time
module information (i.e. description, revision, etc) and configuration.
Assembly 101 is produced for a polled connection. Assembly 102 is
produced for a Change Of State (COS) connection. Assemblies 103,
104, 107 and 108 are by Explicit message only. Assemblies 105 and
106 are consumed in a polled connection (as directed by parameter
4).
Data may be read (get) or written (set) using an Explicit Message. For
example, to read the Present Channel Data, assembly 101
be requested. The following table shows the words which can be
exchanged.
Instances Services Field
#101 (0x65) Get Present Channel Data
Status
#102 (0x66) Get Stored Channel Data
Status
#103 (0x67) Get Present Channel Data
Stored Channel Data
Status
#104 (0x68) Get Programming Error Code
#105 (0x69) Set/Get Counter Control
Output Control
#106 (0x6a) Set/Get PWM Value
#107 (0x6b) Set/Get PWM Value
Counter Control
Output Control
Table continued on next page.
Very High Speed Counter Module Input and Output Data
Bytes
4
2
4
2
4
4
2
2
1
1
2
2
1
1
Publication 1734-UM003A-EN-P - August 2000
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