Rockwell Automation 1747-SCNR ControlNet Scanner Module Reference Manual - Manual (Page 101)

Publication 1747-RM623D-EN-P - June 2006
Application Examples E-23
The Connection Name by default is Discrete 16 Bit Exclusive
Owner. This is the 16-bit rack connection we want. The first
available I/O addresses are I:3.1 and O:3.1, where the
1747-SCNR scanner is in slot 3 of the processor chassis. The first
available starting I/O addresses have been placed into the Input
Address and Output Address fields, because automatic
addressing was previously selected in the Auto Address
Preference screen.
Words I:3.0 and O:3.0 are reserved. Note that the input data
from the 1746-IA16 module are found in the processor’s input
image word I:3.3. The output data written to the 1746-OB16
module will be from the processor’s output image word O:3.2.
You must also enter a value in the Status Address field. This field
supplies Connection Status information to the processor for each
unique connection. The bit address for this field must be an
even number, because two consecutive bits are used as status
for each connection. The even numbered bit indicates whether
the connection is open or closed and the odd numbered bit
indicates whether the connection is in normal operation or Idle
mode. In this example, the starting address chosen is the first
available bit pair, M1:3.600/00.
IMPORTANT
There is a two-word offset for input data for rack
connections. Therefore, for this example, the input data
for the input module in slot 1 of the remote 1747-ACNR15
chassis will be written to I:3.3 in the SLC processor’s input
image.
The starting input address configured in RSNetWorx for
ControlNet software for this rack connection was I:3.1, but
I:3.1 and I:3.2 are used for status information. Therefore,
the actual input data begins after the two words of status
information. I:3.4 and I:3.5 are not used in this example
because an output module resides in slot 2 and an analog
module resides in slot 3.
Also, note that there is no offset for the outputs in a rack
connection. O:3.2 is the output image word written to the
output module located in slot 2 of the 1747-ACNR15
chassis. In addition, no offset applies to module
connections at all.