1.1
How To Use This Manual
General
The Benshaw Remote RTD Module manual provides the following information;
•
Product Description.
•
Specifications.
•
Installation.
•
Use.
How To Use This Manual
The Benshaw Remote RTD Module manual is divided into 4 sections;
•
Introduction.
•
Technical Information.
•
Installation.
•
Operation.
1.2
Product Description
General
The Remote RTD Module is designed to monitor up to 8 RTDs and report their
temperatures across a serial communications link.
Features
The RTD Module provides the following features;
•
Monitors up to 8 3-wire RTDs.
•
Lead Resistance Compensation.
•
RTD open detection.
•
RTD shorted detection.
•
Modbus communications over RS-485.
1.3
Theory of Operation
General
The Remote RTD Module makes a compensated measurement of a RTD (Resistive
Temperature Device). This is accomplished by using three wires to connect the RTD to
the module.
The Remote RTD module provides 10mA of current from H (Hot) and C
(Compensation) terminals. The two currents add at the RTD and 20mA is returned to
the R (Return) terminal. The following diagram illustrates this;
4
1. INTRODUCTION
R
C
H
Remote
RTD
Module
RTD
10mA
20mA
10mA
Compensation
Return
Hot
