Rockwell Automation 1758-RTU202 DataSite Software User Manual FRN 1.2 - Manual (Page 323)

323 Publication 1758-UM002D-EN-P - October 2010
Chapter
5
Enron Modbus Protocol for the 1758-FLO
DataSite Controller
The Modbus protocol is designed as a means to communicate control data
between controllers and sensors using an RS232 port. The Enron Modbus
protocol, used in the oil and gas industry, is based on the Modbus ASCII and
Modbus RTU protocols.
The 1758-FLO DataSite controllers support Enron Modbus and standard
Modbus protocols on the same serial port. The standard Modbus protocol
and the Enron Modbus protocol use different station addresses. This feature
allows the standard PC host to communicate with the 1758-FLO controller in
the standard Modbus protocol and an Enron Modbus host to communicate
with this controller at the same time.
The 1758-FLO DataSite controllers support the following Enron Modbus
function codes.
Enron Modbus function codes and descriptions
Command Description
3 Read multiple numeric variables
6 Write single numeric variable
16 Write multiple numeric variables