ProSoft Technology AN-X-MOD - Manual (Page 28)

Page 24 AN-X-MOD (Master) November 2011
Exchanging Scheduled Data with a ControlLogix
A Modicon S908 remote I/O network can contain up to 2048 words of
input data and 2048 words of output data (32 drops x 64 words per drop).
Each scheduled connection with a ControlLogix contains at most 250
words of input data and 248 words of output data. In order to be able to
scan the largest possible Modicon network, the AN-X-MOD (Master)
module supports multiple scheduled connections with a ControlLogix
processor over Ethernet.
The AN-X-MOD (Master) module behaves like a 17-slot ControlLogix
rack with an ENBT/A module in slot 16 and generic modules in slots 0 to
15.
A ControlLogix processor can open scheduled connections to each of
these 16 generic modules. Each scheduled connection consists of up to
248 words of output data from the ControlLogix processor to the AN-X
and up to 250 word of input data from the AN-X to the ControlLogix
processor.
Each connection can have its own RPI, from 5 to 750 ms.
In general, you should try to keep the number of connections small.
There is significant overhead in opening and maintaining each
connection.
You map the inputs and outputs for the Modicon I/O modules on the
S908 network to the data for these scheduled connections. AN-X can
create the mappings automatically or you can create a mapping
configuration manually.
You can have AN-X create the mapping file automatically, then edit the
file to better suit your application. For example, in order to make the
most efficient use of the available Ethernet bandwidth, you can organize
the data so that items that must update quickly are mapped to
connections with short RPIs and items that are less time critical are
mapped to connections with longer RPIs.
In addition, the AN-X module has diagnostic data that can be mapped to
ControlLogix scheduled input data.
The mapping file can also contain options that apply to the entire
configuration.
Anything after a semicolon is treated as a comment.
Mapping I/O Data
You map Modicon input and output data to the ControlLogix scheduled
data by creating a comma separated variable file that defines the
mappings.