Rockwell Automation 56AMXN/B ControlLogix AutoMax Comm Module - Manual (Page 44)

Page 44 AutoMax DCSNet /RE RIO Module
Publication number 56AMXN-UM002A-EN-P November 2002
In the source tag, the data consists of:
# of attributes
First Attribute #
Second attribute #
And so on.
The reply consists of:
# of attributes
First Attr #
Status for first attribute
Data[32] for first attribute
Second Attr #
Status for second attribute
Data[32] for second attribute
and so on.
The attribute status reflects the status of the drop in the active drop list.
The value if the drop status bit for this drop is 0 (not present) or 1 if the
drop status bit for this drop is 1 (present).
The number of attributes whose data you can read at one time is limited
by the maximum message length of approximately 500 bytes, which
corresponds to a maximum of 7 attributes (drops).
Example
For example, to read registers 0-31 on drops 1, 4 and 7, set up a MSG
instruction with the following parameters:
Message
Type CIP generic
Service Type Custom
Service Code 3
Class (hex) C4h
Instance 1
Attribute (hex) Leave blank
Source
Element Source tag name
Source 2 + 3 * 2 = 8