Rockwell Automation PLC-5 Fieldbus Solutions for Integrated Architecture User Manual - Manual (Page 285)

Publication 1757-UM006A-EN-P May 2002
1788-CN2FF Installation Example F-37
Figure F.4 Device Information Screen
2. Expand the window so you can read all the columns.
This screen is the reason we recommend using a high resolution
monitor and short Function Block names.
The Device Info screen describes the format of the data that is
produced by the 1788-CN2FF on ControlNet.
The Offset column indicates the offset in bytes from the beginning of
the transmission to each piece of data from a Fieldbus devise.
Schedule Data Transmission to Controllers with RSNetworx
You must use RSNetworx to schedule the transmission of data to the
controller, RSLogix 5000, or Control Builder. Place the data in an
integer data table, like N13, starting at location N13:0.
You may need to add some devices to the configuration so we
recommend that you leave some empty words in the data table. Store
the data from each of the linking devices at an easy to calculate
location like N13:0, then store the data from the next CN2FF at
N13:50, the data from the next CN2FF at N13:100, etc.
PLC-5 Data Manipulation
Figure F.4 on page F-37 shows that the Floating Point value of each
Analog Input from the Fieldbus devices is a four byte ControlNet Float
when it goes on the wire. When this four byte value arrives at the
PLC-5, it is stored in an integer file in a PLC-5 word format. That
CN2FF interface name
Connection Port Number
Used with ControlNet
Message Instructions
Offset in bytes from the
start of the ControlNet
produced data Length of
value in
bytes