ADS Intrinsically-Safe TRITON+, Installation, Operation And Maintenance Manual

Page: 306 / 424

9-1
C H A P T E R 9
Modbus
Many newer SCADA and process control systems connect either
directly or wirelessly to measurement devices through a serial
connection or wireless modem to quickly access process values.
One of the industry standard protocols through which this occurs is
Modbus . The ADS
® ™
monitor serves as a Modbus slave
device and provides process values based on Modbus holding
registers through an ExPAC interface or wirelessly through the
internal cellular modem.
This chapter contains essential connection and reference
information regarding communication and data exchange through a
serial connection involving the
, ExPAC/XBUS, and
RTU. It specifically addresses the Modbus data registers.
For Modbus wireless data exchange, refer to Chapter
Note: An RTU (remote terminal unit) is an example of
the kind of customer-supplied equipment that uses Modbus
acquired data. Many other types of equipment may be
connected to
monitors; however, all will
communicate as described. A PLC (programmable logic
controller), an I/O (input/output) server, or other
instruments, such as the Telog
®
Ru-33, may be used in
place of an RTU. ADS
®
references the RTU in this
manual primarily because it is the most common type of
end-point hardware used with SCADA systems.