Rockwell Automation 57C442 Data Highway Plus Interface Module - Manual (Page 19)

4-1
4.0 PROGRAMMING
The Data Highway Plus network is a token-passing network, which
means that any device on the network can initiate communication with
any other device. Each node can also pass one word of global data with
the token. This global data is available to all other nodes on the
network.
Up to 64 devices can be connected directly to the network, with station
numbers ranging from 0 to 77 octal. Duplicate addresses are not
allowed. The network communication rate can be 57.6, 115.2, or 230.4
Kbaud, depending upon the user configuration.
This section describes how the data is organized in the module and
provides examples of how the module is accessed by the application
software. For more detailed information on programming, refer to the
AutoMax Programming Language manuals.
4.1 Register Organization
The Data Highway Plus Interface module contains dual-port memory
that can be accessed through the AutoMax rack backplane by
application tasks running on the AutoMax Processor as well as by the
microprocessor on the module. The memory organization is as shown
in the following diagram. The following sections describe the different
register areas in more detail.
Registers Description
0-3 Reserved
4-63 Status and control registers
64 – 1063 Binary file B3
1064 - 1087 Reserved
1088 - 2087 Binary file B4
2088 - 3087 Binary file B5
3088 - 3583 Reserved
3584 - 4095 Reserved
4096 – 4352 Global data registers
4353 - 4383 Reserved
4384 - 16383 Integer files N7 – N18
Figure 4.1 – Dual Port Memory Map
!
ATTENTION: Registers and bits in the data highway plus
interface module that are described as “read only” or for “system
use” only must not be written to by the user.Writing to these
registers and bits may result in improper system operation.
Failure to observe this precaution could result in bodily injury.