Rockwell Automation 56AMXN/B ControlLogix AutoMax Comm Module - Manual (Page 40)

Page 40 AutoMax DCSNet /RE RIO Module
Publication number 56AMXN-UM002A-EN-P November 2002
of service, instance, and attribute makes it possible to read or write the
data on any DCS drop.
There are instructions that read and write the data on single drops and
instructions that read and write data on multiple drops.
Note that these instructions allow you to write to areas of the network
memory map that AutoMax would not allow.
If you read or write data that is also mapped into the scheduled data, the
data read or written with the MSG instruction will be overwritten when
the scheduled data updates.
Refer to the ControlLogix documentation for general information on the
object model used in ControlLogix processors.
Instances
The instance is used to distinguish between registers 0-31 and registers
32-63. For example, if the MSG instruction is performing a write, it can
write to only one group of registers or the other, depending on whether it
is a DCS master or DCS slave.
Instance Description
1 Registers 0-31
2 Registers 32-63
Table 7 DCS Data Object Instances
Attributes
Attributes are used to select the drop the MSG instruction is reading from
or writing to.
Attribute Description
1-55 Selects the drop number. Note that you enter the
attribute in hex in RSLogix 5000
Table 8 DCS Data Object Instance Attributes
Instance Services
The DCS Data Object supports the following services, which are
described in more detail in the sections which follow.
Service
(hex)
Name Function
03h Get Attribute List Get the data for up to 7 drops