Siemens 505-2557 installation and operation guide Wiring Diagram for Millivolt Measurements

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Ground at One End Only

Figure 2-6 Wiring Diagram for Millivolt Measurements

Connecting the Siemens Energy & Automation, Inc. recommends that all signal wires be

Shield Wiring shielded twisted±pair with a foil wrap shield and a separate drain wire and that they be installed in a metallic conduit. Use Belden cable 8761 or equivalent which contains foil wrap shield and a separate drain wire. The shield and the foil wrap should be twisted together and should be terminated at only one end. The other end should be left in an open circuit condition. Siemens recommends that the shield be terminated at the PLC end of the signal wire. Special components are installed on the module to aid in the rejection of noise.

When entering the industrial cabinet the shield wires should be routed from the main terminal strip all the way to the PLC. Signal leads that do not maintain a shield from the terminal strip to the PLC act as antennas and are susceptible to radiated and conducted emissions in the cabinet. Unprotected cables may introduce measurement errors in the module.

The fron connector on the module contains a G terminal which may be used for the shield wire if the installation is in a noise free environment. If the installation is in an extremely noisy environment Siemens strongly recommends that the shield wires be terminated to the PLC chassis ground.

This product has been exhaustively tested to maximize its ability to reject noise from inductive sources as well as showering arcs, fast transients and other high frequency generators and has determined that the best performance results from connecting all shield wires together at the PLC module and terminating this single wire to the chassis ground with a large current capacity conductor. The PLC chassis should then be wired to earth ground with a large current capacity conductor. Siemens recommends using a #8 gauge wire from the PLC chassis to the earth ground connection.

SIMATIC 505±2557 Installation and Operation Guide

Installation 2-11

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Contents Simatic Copyright 1998 by Siemens Energy & Automation, Inc Manual Publication History List of Effective Pages Contents Iv Contents List of Figures List of Tables Preface Agency Approvals EuropeanCommunity CE ApprovalDescription 100 Ohm, 10 Ohm, 120 Ohm RTDs, or Millivolt InputsOperating Modes Word Input to the PLC from the Module RTD Input to Digital Conversion Scale UnitsEffect SignalsOut-of-Range Input Effect of Voltage Input 10 Ohm Copper Resolution Input ResolutionCalculating the I/O Base Power Budget Installing and Configuring the ModuleSelecting 2 and 3 Wire or 4 Wire Operation Installing and Configuring the Module Configuring Selecting Temperature orMillivolt Input Selecting Degrees Celsius orFahrenheit Selecting DataConfiguration Jumper Locations Module Into InsertingBase Wiring the Input Connectors Copper Wire Table at 25 Degrees CelsiusPress In Wiring Connector Wiring Diagram for 2, 3, or 4 Wire RTD Wiring Diagram for Millivolt Measurements Cable Grounding Example I/O Configuration Chart Advanced Function Programming Advanced Software Functions IntroductionOverview AdvancedConfiguration Setting the ModuleJumper Controller I/O LoggingMemory Internal Register Structures Input and Output Register OffsetsInput Registers Input Channel DataInput Flag Bits Peak/Valley Hold Input WordsOutput Data Registers AveragingControl Registers Function Enable BitsInputs Discrete Handshake Inputs Outputs Data Identification BitsLoading Data into the Simatic 505±2557 Module Data Loading ProcessSample Low and High Alarm Setpoints Identifying the Data Being Transferred 11 Enabling the Functions Loaded Loading Programs into the I/O Module 13 Startup Relay Ladder Logic Page When Using Timing Overhead for Functions EnabledTiming Considerations Timing ConstraintsDefault Values Default Function ValuesDefault Function Values for Simatic 505±2557 Additional Information about Each FunctionAlarm Setpoints DegreesCentigrade or Degrees FahrenheitDigital Filtering Peak and Valley AveragingHold Hold Reset Flag BitsFunction PrecedenceTroubleshooting 10 Troubleshooting Flow Diagram Symptom Probable Cause Corrective ActionI/O Register Quick Reference 17 I/O Register Quick ReferenceOr K Memory Configuration Tables Page Addressing Worksheet Items Unique to the Simatic 505±2557 Module 18 Open RTD Status BitsTroubleshooting Specifications Table B-1 SpecificationsSpecifications subject to change without notice Jumper Settings Log Sheet Customer Response Business Reply Mail