Instruction manual

Introduction
2 025-9209
Table 1. Digital and Analog I/O Capability
I/O 1708 1716 1700
Digital In 8 16 0
Digital Out 8 16 4
Analog In 4 8 0
Analog Out 0 4 0
The RTU is initialized through the RS-232 port, which allows the user to customize the
parameters for each RTU to best fit the application.
SYSTEM DESCRIPTION
Model 1700
Control Unit
PC, CRT,
Printer or Status
Panel
Transceiver
Transceiver
Transceiver
Transceiver
1708/1716
RTU
Unit #1
I/O Lines
1708/1716
RTU
Unit #2
I/O Lines
1708/1716
RTU
Unit #9
I/O Lines
Figure 1. A Typical System with One Controller and Nine RTUs
Figure 1 depicts a model system that might be used to monitor and control pump stations.
This system gives the user PC or status panel control of turning pumps on or off and of
polling the sites to verify status and to receive alarm reports of pump failures or
communications failures.
MODBUS SYSTEM
MODBUS is an industry-standard protocol used to transfer commands and data. An example
of a SCADA program that uses the MODBUS protocol is Lookout (by National Instruments).
Many PLCs also use the MODBUS protocol. A MODBUS option for the Model 1700
controller allows the controller and Zetron RTUs to be used in a MODBUS system.