Siemens 505-2557 Advanced Software Functions, Introduction, Overview

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3.1Advanced Software Functions

Introduction

As PLC control systems become more complex, the need for real-time

 

processing of analog signals is needed at the I/O level. Current

 

implementations using the 505 controllers utilize analog alarm blocks

 

and/or special function programs within the controller. The SIMATIC

 

505±2557 analog input module from Siemens Energy & Automation, Inc.,

 

can reduce the program complexity and scan time by performing this signal

 

processing in the module.

 

Scaling, alarming, peak/valley hold, digital filtering, and averaging are

 

available on a per-channel basis and are selected through a simple PLC

 

configuration routine. When these advanced functions are enabled, the

 

module logs in as 16X / 16Y / 32WX / 32WY. A jumper on the module selects

 

the standard 16WX login or the high-density advanced function interface.

Overview of the

Each of these functions can be selected on a per-channel basis, and each

Advanced

channel can have any function in any combination, e.g. alarming on a scaled

Functions

value which is digitally filtered and set for peak hold. (See Section 3.4 for

 

timing considerations.)

 

Scaling Each channel can be configured with low and/or high scale value.

 

A flowmeter that outputs 0 mA @ 5 cfm and 20 mA @ 50 cfm would have a

 

low scale of 5 and a high scale of 50. An operator interface attached to the

 

controller could then read the analog values directly in engineering units

 

without having to run a Special Function program to scale the input.

 

Alarming Each channel can be assigned a low and/or high alarm value.

 

No analog alarm blocks are needed in the controller. Alarming occurs

 

real-time as the signal is processed by the module. Two WX words are used

 

to indicate high and low alarm conditions (bit 1 = channel 16, etc.). A third

 

WX word is the logical OR of the high and low alarms.

 

Peak/valley hold The peak or valley of a rapidly changing analog signal

 

has been impossible to detect unless an external circuit was used. The

 

SIMATIC 505±2557 makes possible the detection of a peak or valley and

 

holds that value until reset by the controller. The peak/valley measurement

 

is available to the controller at the same time as the currently measured

 

analog value.

 

Averaging This option is used to ªclean upº a signal that is at a steady

 

state, e.g., a sensor riding on a liquid tank with riplets. The user specifies

 

how many signal scans to average and this value is presented to the

 

controller.

 

Digital filtering This has the effect of a moving average operation

 

(actually it is an Infinite Impulse Response filter), and is useful to smooth

 

out the high frequency noise on a changing analog signal. See Section 3.4.

3-2

Advanced Function Programming

SIMATIC 505±2557 Installation and Operation Guide

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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 UnitsOut-of-Range Input SignalsEffect Effect of Voltage Input 10 Ohm Copper Resolution Input ResolutionSelecting 2 and 3 Wire or 4 Wire Operation Installing and Configuring the ModuleCalculating the I/O Base Power Budget Installing and Configuring the Module Configuring Millivolt Input Temperature orSelecting Selecting Degrees Celsius orFahrenheit Selecting DataConfiguration Jumper Locations Base InsertingModule Into 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 AdvancedJumper Setting the ModuleConfiguration Memory LoggingController I/O Internal Register Structures Input and Output Register OffsetsInput Registers Input Channel DataInput Flag Bits Peak/Valley Hold Input WordsOutput Data Registers AveragingInputs Function Enable BitsControl Registers 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 Hold AveragingPeak and Valley 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
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