Siemens 505-2557 Timing Considerations, Timing Constraints, When Using

Page 48

3.4Timing Considerations

	Without any of the advanced features enabled, the SIMATIC 505±2557
	module will update all 16 points in less than 6 msec. With all functions
	enabled for all 16 points, the module will update all 16 channels in less than
	56 msec. Each function has a specific overhead associated with it and your
	application should consider the time delays to ensure that there is adequate
	time allowed for the processing of data.
Timing Constraints	Table 3-7 shows a chart of the overhead required for all 16 channels when
When Using	each of the advanced functions is enabled. Operations such as scaling and
Advanced	offset mode require the greatest amount of time due to the multiplication
Functions	and division in the microcomputer.
	Table 3-7 Timing Overhead for Functions Enabled

Functions Enabled in Enhanced Mode (32 WX and 32 WY, 16 X and 16 Y)

Time for All 16 Channels


None	6.5 msec

Low alarm	7.73 msec

High alarm	7.73 msec

Scaling	27.1 msec

Offset mode	27.1 msec

Filtering	8.97 msec

Averaging	7.85 msec

Averaging reset (16 channels)	41.8 msec

Peak hold	7.65 msec

Valley hold	7.65 msec


16 WX MODE


No digital filtering	5.80 msec

Filtering enabled	8.20 msec

3-18 Advanced Function Programming

SIMATIC 505±2557 Installation and Operation Guide

Image 48

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 UnitsSignals EffectOut-of-Range Input Effect of Voltage Input 10 Ohm Copper Resolution Input ResolutionInstalling and Configuring the Module Calculating the I/O Base Power BudgetSelecting 2 and 3 Wire or 4 Wire Operation Installing and Configuring the Module Configuring Temperature or SelectingMillivolt Input Selecting Degrees Celsius orFahrenheit Selecting DataConfiguration Jumper Locations Inserting Module IntoBase 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 AdvancedSetting the Module ConfigurationJumper Logging Controller I/OMemory Internal Register Structures Input and Output Register OffsetsInput Registers Input Channel DataInput Flag Bits Peak/Valley Hold Input WordsOutput Data Registers AveragingFunction Enable Bits Control RegistersInputs 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 Averaging Peak and ValleyHold 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