Chapter 4, Modbus register definition, Chapter – Rockwell Automation 1758-RTU202 DataSite Software User Manual FRN 1.2 User Manual
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Publication 1758-UM002D-EN-P - October 2010
Chapter
4
Extension Modbus Protocol for DataSite
Controllers (1758-FLO)
This chapter describes communication with a SCADA system using the
Extension Modbus protocol. The Extension Modbus protocol is fully
compatible with standard Modbus. All data interchanges, including flow
history data, are accomplished using the Extension Modbus protocol.
Modbus Register Definition
The DataSite controller uses the Modbus address to share data between C
programs and communication protocols. The section describes the Modbus
registers used in the DataSite controller, including general purpose registers
and user-assigned registers.
Data formats
Data Type
Number of Registers
Required
Description
u_char
1
Unsigned integer in the range 0…255.
u_short
1
Unsigned integer in the range 0…65535.
u_int
2
Unsigned integer in the range
0…4294967295.
float
2
IEEE single precision floating-point number.
Data attributes
Attribute
Description
RW
Read/write
RO
Read-only
W
Write
R
Read