Siemens 505-2557 installation and operation guide Hold Reset, Flag Bits

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Peak and Valley	Outputs Y28 and Y29 are used to reset the valley or peak hold functions.
Hold Reset	The operation during reset is dependent on whether the hold function is
	enabled for each individual channel.
	Figure 3-15 shows how the peak value and the valley value react during
	reset.

	Peak or Valley Hold Function
	Enabled	Reset to current input value
	Disabled	Reset to zero

	Figure 3-15 Peak/Valley Reset Truth Table
Flag Bits	When not using peak or valley hold, WX49 ± WX54 return flag bits for each
	of the functions, and each of the channels may be interrogated with ladder
	logic instructions.
	The flag bits correspond to the 16 channels in the module. The LSB or bit 16
	corresponds to channel 1, and the MSB or bit 1 corresponds to channel 16.
	See Figure 3-16.

Bit #

MSB																LSB

1		2	3	4	5	6	7	8	9	10	11	12	13	14	15	16

Channel # 16 15 14 13 12 11 10 9 8 7 6 5 4 3

2 1

Figure 3-16 Mapping Bit Position to Channel Number

Alarm flags (WX49) The alarm flag bit is the logical OR of the low alarm bit (WX5) and the high alarm bit (WX50) for each channel. This allows one simple check to determine if an alarm exists on a channel. These alarm bits reset automatically when the alarm condition is no longer true. In the event that an alarm exists on a channel, the ladder logic may determine whether the alarm has reached the low alarm or the high alarm.

SIMATIC 505±2557 Installation and Operation Guide

Advanced Function Programming 3-23

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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 European Agency ApprovalsCommunity CE Approval100 Ohm, 10 Ohm, 120 Ohm RTDs, or Millivolt Inputs DescriptionOperating Modes Word Input to the PLC from the Module Scale Units RTD Input to Digital ConversionOut-of-Range Input SignalsEffect Effect of Voltage Input 10 Ohm Copper Input Resolution 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 Celsius or Selecting DegreesFahrenheit Selecting DataConfiguration Jumper Locations Base InsertingModule Into Copper Wire Table at 25 Degrees Celsius Wiring the Input ConnectorsPress 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 Introduction Advanced Software FunctionsOverview AdvancedJumper Setting the ModuleConfiguration Memory LoggingController I/O Input and Output Register Offsets Internal Register StructuresInput Registers Input Channel DataPeak/Valley Hold Input Words Input Flag BitsAveraging Output Data RegistersInputs Function Enable BitsControl Registers Discrete Handshake Inputs Data Identification Bits OutputsData Loading Process Loading Data into the Simatic 505±2557 ModuleSample 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 Timing Overhead for Functions Enabled When UsingTiming Considerations Timing ConstraintsDefault Function Values Default ValuesDefault Function Values for Simatic 505±2557 Additional Information about Each FunctionDegrees Alarm SetpointsCentigrade or Degrees FahrenheitDigital Filtering Hold AveragingPeak and Valley Flag Bits Hold ResetPrecedence FunctionTroubleshooting Symptom Probable Cause Corrective Action 10 Troubleshooting Flow Diagram17 I/O Register Quick Reference I/O Register Quick ReferenceOr K Memory Configuration Tables Page Addressing Worksheet 18 Open RTD Status Bits Items Unique to the Simatic 505±2557 ModuleTroubleshooting Table B-1 Specifications SpecificationsSpecifications subject to change without notice Jumper Settings Log Sheet Customer Response Business Reply Mail