Rice Lake Allen-Bradley Remote I/O - Manual (Page 5)

Introduction 1
About This Manual
This manual provides information needed to install
and use the Rice Lake Weighing Systems Remote I/O
Interface card. The Remote I/O Interface allows
520 ,
720i ® , 820i ® , and 920i ® indicators to communicate
w i t h P L C ® a n d S L C ™ c o n t r o l l e r s u s i n g t h e
Allen-Bradley ® Remote I/O network. 1 See the 520 ,
720i , 820i , or 920i Installation Manual for additional
installation information and detailed descriptions of
indicator functions.
The Remote I/O Interface card is installed inside the
indicator enclosure. Installation in NEMA 4X
stainless steel enclosures permits use in washdown
environments.
W arning
Some procedures described in this manual
require work inside the indicator enclosure.
These procedures are to be performed by
qualified service personnel only.
Authorized distributors and their employees
can view or download this manual from the
Rice Lake Weighing Systems distributor site
at
www.ricelake.com .
1.0 Introduction
The Remote I/O Interface returns weight and status information from the 520 , 720i , 820i , or 920i indicator to the
PLC controller. The Remote I/O Interface also provides the PLC programmer with limited control of indicator
functions. Indicator configuration and calibration cannot be performed through the Remote I/O Interface.
The Remote I/O Interface behaves as a node adapter device to the master PLC, appearing as a quarter rack of I/O.
The PLC controller and Remote I/O Interface communicate using a quarter rack of data slots (4 slots with 8 bits
of input, 8 bits of output per slot). Each pair of slots corresponds to a “module group”, one input and one output
word. The Remote I/O Interface contains two module groups and therefore communicates two words of data.
The PLC controller sends commands to the indicator through the Remote I/O Interface by writing the commands
to the output image table, and reads returned weight and status data from the input image table. These actions are
referred to as discrete transfers. See Section 3.0 for information about using discrete transfer commands.
Block transfers are accomplished by sending a block write command followed by a block read command.
Separate data files are set up for block commands. The length of these files depends on the length of the data
being read or written. See Section 4.0 for information about using block transfer commands.
1. Allen-Bradley ® , PLC ® , and SLC ™ are trademarks of
Allen-Bradley Company, Inc., a Rockwell International
company.