Tektronix DAS-Scan Function Call Driver Users Guide

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DAS-Scan Function Call Driver

USER’S GUIDE

DAS-Scan

Function Call Driver

User’s Guide

Revision A – July 1996

Part Number: 94890

New Contact Information

Keithley Instruments, Inc.

28775 Aurora Road

Cleveland, OH 44139

Technical Support: 1-888-KEITHLEY

Monday – Friday 8:00 a.m. to 5:00 p.m (EST)

Fax: (440) 248-6168

Visit our website at http://www.keithley.com

The information contained in this manual is believed to be accurate and reliable. However, Keithley Instruments, Inc., assumes no responsibility for its use or for any infringements of patents or other rights of third parties that may result from its use. No license is granted by implication or otherwise under any patent rights of Keithley Instruments, Inc.

KEITHLEY INSTRUMENTS, INC., SHALL NO T BE LIABLE FOR ANY SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES RELATED TO THE USE OF THIS PRODUCT. THIS PRODUCT IS NOT DESIGNED WITH COMPONENTS OF A LEVEL OF RELIABILITY SUITABLE FOR USE IN LIFE SUPPORT OR CRITICAL APPLICATIONS.

Refer to your Keithley Instruments license agreement for speciﬁc warranty and liability information.

MetraByte is a trademark of Keithley Instruments, Inc. All other brand and product names are trademarks or registered trademarks of their respective companies.

All rights reserved. Reproduction or adaptation of any part of this documentation beyond that permitted by Section 117 of the 1976 United States Copyright Act without permission of the Copyright owner is unlawful.

Keithley MetraByte Division

Keithley Instruments, Inc.

440 Myles Standish Blvd. Taunton, MA 02780

FAX: (508) 880-0179

Telephone: (508) 880-3000

●

Preface

The DAS-Scan Function Call Driver User’s Guide provides information to help you write application programs for the DAS-Scan system using the DAS-Scan Function Call Dri ver. The DAS-Scan Function Call Driver supports the following Windows  -based languages:

●

Microsoft Borland

●

Microsoft Visual Basic

●



Visual C++  (up to Version 1.52)



C/C++ (Version 4.0 and 4.5)



for Windows (Version 3.0 and Version 4.0)

The manual is intended for application programmers using a DAS-Scan system with an IBM



PC AT



or compatible computer. It is assumed that you have read the DAS-Scan User’ s Guide to familiarize yourself with the system’s features, and that you have completed the appropriate hardware installation and conﬁguration. It is also assumed that you are experienced in programming in your selected language and that you are familiar with data acquisition principles.

The DAS-Scan Function Call Driver User’s Guide is organized as follows:

●

Chapter 1 contains the information needed to install the DAS-Scan Function Call Driver, a summary of the DAS-Scan Function Call Driver functions typically used when programming a DAS-Scan system, a series of ﬂow diagrams illustrating the procedures typically used when programming a DAS-Scan system, and information on how to get help.

Chapter 2 contains conceptual information about the DAS-Scan

●

Function Call Driver functions typically used when programming a DAS-Scan system.

vii

Chapter 3 contains conceptual information about additional

●

DAS-Scan Function Call Driver functions you can use when programming a DAS-Scan system.

Appendix A contains instructions for con v erting counts to voltage and

●

for converting counts to temperature.

An index completes this manual.

Keep the following conventions in mind as you use this manual:

●

References to Windows apply to Windows 3.1, Windows 3.11 for Workgroups, and Windows 95. When a feature applies to a speciﬁc Windows version, the complete version name is used.

●

Keyboard keys are represented in bold.

viii

Table of Contents

Preface

Getting Started

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-2

Setup and Installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-2

Summary of Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-4

Programming Flow Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . .1-6

Preliminary Steps for All Analog Input Operations . . . . . . . .1-7

Steps for a Single-Mode Analog Input Operation. . . . . . . . . .1-8

Steps for a DMA-Mode Analog Input Operation . . . . . . . . . .1-9

Getting Help. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-14

Available Operations

System Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-1

Initializing the Driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-1

Initializing a Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-2

Generating a Windows Event . . . . . . . . . . . . . . . . . . . . . . . . .2-3

Retrieving Revision Levels . . . . . . . . . . . . . . . . . . . . . . . . . . .2-4

Handling Errors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-4

Analog Input Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-5

Operation Modes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-5

Single Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-5

DMA Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-5

Accessing a Frame . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-7

Memory Allocation and Management. . . . . . . . . . . . . . . . . . .2-9

Gains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-11

Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-12

Addressing Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-12

Specifying a Single Channel . . . . . . . . . . . . . . . . . . . . . .2-17

Specifying a Group of Consecutive Logical Channels. . .2-17

Specifying Channels in a Channel-Gain Queue. . . . . . . .2-18

Pacer Clock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-19

Internal Pacer Clock. . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-20

External Pacer Clock . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-21

iii

Triggers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-22

Internal Trigger. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-23

External Digital Trigger. . . . . . . . . . . . . . . . . . . . . . . . . .2-23

Hardware Gate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-24

Additional Features

Summary of Additional Functions. . . . . . . . . . . . . . . . . . . . . . . .3-2

Additional Programming Flow Diagrams . . . . . . . . . . . . . . . . . .3-3

Preliminary Steps for All Analog Input Operations . . . . . . . .3-4

Steps for a Single-Mode Analog Input Operation. . . . . . . . . .3-5

Steps for an Interrupt-Mode Analog Input Operation. . . . . . .3-6

Steps for a DMA-Mode Analog Input Operation . . . . . . . . .3-12

Performing an Interrupt-Mode Operation . . . . . . . . . . . . . . . . .3-19

Accessing a Frame . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-20

Reserving Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-20

Specifying Channels and Gains . . . . . . . . . . . . . . . . . . . . . .3-22

Specifying a Pacer Clock . . . . . . . . . . . . . . . . . . . . . . . . . . .3-23

Specifying a Trigger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-23

Enabling a Hardware Gate . . . . . . . . . . . . . . . . . . . . . . . . . .3-23

Specifying Continuous Mode. . . . . . . . . . . . . . . . . . . . . . . . . . .3-23

Reserving Large or Multiple Memory Buffers . . . . . . . . . . . . .3-24

Specifying Burst Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-25

Using the Burst Mode Conversion Clock . . . . . . . . . . . . . . . . .3-26

Specifying Pre-Trigger Acquisition . . . . . . . . . . . . . . . . . . . . . .3-26

Specifying About-Trigger Acquisition. . . . . . . . . . . . . . . . . . . .3-28

Data Formats

Converting Counts to Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . A-1

Converting Counts to Temperature . . . . . . . . . . . . . . . . . . . . . . A-3

Index

List of Figures

Figure 2-1. Frame-Based Operation. . . . . . . . . . . . . . . . . . . . .2-7

Figure 2-2. Digital Trigger Conditions. . . . . . . . . . . . . . . . . .2-23

List of Tables

Table 1-1. Summary of Functions. . . . . . . . . . . . . . . . . . . . . .1-4

Table 2-1. A/D Frame Elements . . . . . . . . . . . . . . . . . . . . . . .2-9

Table 2-2. Analog Input Ranges . . . . . . . . . . . . . . . . . . . . . .2-11

Table 2-3. Virtual Boards and Logical Channels . . . . . . . . .2-13

Table 3-1. Summary of Additional Functions. . . . . . . . . . . . .3-2

Table 3-2. Functions Used to Assign Starting Addresses

in Interrupt Mode. . . . . . . . . . . . . . . . . . . . . . . . .3-22

Table A-1. Span Values For Data Conversion Equations . . . A-2

Table 1-1. Summary of Functions. . . . . . . . . . . . . . . . . . . . . .1-3

Table 2-1. A/D Frame Elements . . . . . . . . . . . . . . . . . . . . . . .2-5

Table 2-2. Functions Used to Assign Starting Address . . . .2-14

Table 2-3. Analog Input Ranges . . . . . . . . . . . . . . . . . . . . . .2-15

Table 2-4. Virtual Boards and Logical Channels . . . . . . . . .2-16

Table 3-1. Functions Used to Assign Starting Addresses. . . .3-4

Table A-1. Span Values For Data Conversion Equations . . . A-2

Figure 2-1. Interrupt-Mode Operation . . . . . . . . . . . . . . . . . . .2-4

Figure 2-2. Analog Trigger Conditions . . . . . . . . . . . . . . . . .2-27

Figure 2-3. Using a Hysteresis Value. . . . . . . . . . . . . . . . . . .2-29

Figure 2-4. Digital Trigger Conditions. . . . . . . . . . . . . . . . . .2-30

Getting Started

This chapter contains the following sections:

Overview - a description of the DAS-Scan Function Call Driver.

●

Setup and Installation - a list of the tasks you should perform before

using the DAS-Scan Function Call Driver.

●

Summary of Functions - a brief description of the DAS-Scan

Function Call Driver functions that are typically used when programming a DAS-Scan system.

●

Programming Flow Diagrams - an illustration of the procedures

you will typically follow when programming a DAS-Scan system using the DAS-Scan Function Call Driver.

●

Getting Help - information on how to get help when installing or

using the DAS-Scan Function Call Driver.

1-1

Overview

The DAS-Scan Function Call Driver is a library of data acquisition and control functions that is part of the ASO-SCAN software package. The ASO-SCAN software package includes the following:

●

Dynamic Link Libraries (DLLs) of Function Call Driver functions for Microsoft Visual C++, Borland C/C++, and Microsoft Visual Basic for Windo ws.

●

Support ﬁles, containing program elements, such as function prototypes and deﬁnitions of variable types, that are required by the Function Call Driver functions.

Utility programs that allow you to conﬁgure, calibrate, and test the

●

functions of the DAS-Scan system.

●

Language-speciﬁc example programs.

Setup and Installation

Before you use the DAS-Scan Function Call Driver to program your DAS-Scan system, make sure that you have performed the following tasks. Refer to the DAS-Scan User’s Guide for more information.

1. Unpack and inspect the components of your DAS-Scan system.

2. Create a channel map indicating the input signals you want to attach to each of the channels in your DAS-Scan system.

3. Conﬁgure the hardware components, as follows: – On the SCAN-AD-HR board, set the base I/O address switch

(S1) to indicate the appropriate base I/O address, and, if appropriate, set the J6 jumper to indicate an external pacer clock or an external digital trigger/hardware gate.

– On each SCAN-BRD assembly, set the address thumbwheels to

indicate the appropriate assembly address.

– If you are using SCAN-STP-TC screw terminal panels, set the J2

jumpers on each panel to indicate whether you are using cold junction compensation (CJC).

1-2 Getting Started

4. Mount the SCAN-STP screw terminal panels on DIN rails.

5. Attach the input signals to the appropriate SCAN-STP screw terminal panels.

6. Mount the SCAN-CH chassis in a 19-inch rack.

7. Attach one end of each SCAN-CAB-64 cable to the appropriate position in the SCAN-CH chassis. (Do not attach the other end of the SCAN-CAB-64 cables at this point.)

8. Attach a power cord to the power-supply panel of each SCAN-CH chassis.

9. Check the operation of the power supply in each SCAN-CH chassis.

10. Install the SCAN-BRD assemblies in the appropriate SCAN-CH chassis.

11. Make sure that power to the computer is turned OFF.

12. Install the SCAN-AD-HR board in your computer.

13. Attach the SCAN-AD-HR board to your ﬁrst SCAN-CH chassis using the S-1802/M cable.

14. Daisy-chain multiple SCAN-CH chassis, if required, using S-1802/MM cables.

15. Attach the other end of each SCAN-CAB-64 cable to the appropriate SCAN-STP screw terminal panel.

16. Connect an external pacer clock, external digital trigger, or hardware gate, if required, to the J5 connector on the SCAN-AD-HR board using a CAB-SMA-BNC cable.

17. Plug the power cords into the wall, and then power up your computer, the SCAN-CH chassis, and any equipment attached to the SCAN-STP screw terminal panels.

18. Install the ASO-SCAN software package.

19. Specify the conﬁguration options for your DAS-Scan system in the DAS-Scan Conﬁguration Utility.

20. Test the functions of the DAS-Scan system using the DAS-Scan Control Panel.

21. Look at the example programs provided with the ASO-SCAN software package. Refer to the FILES.TXT ﬁle in the installation directory for a list and description of the example programs.

Setup and Installation 1-3

Summary of Functions

Table 1-1 describes the functions in the DAS-Scan Function Call Driver that are typically used to program a DAS-Scan system. For more detailed information about the functions, refer to Chapter 2 of this manual and to the DAS-Scan Function Call Driver online help ﬁle (SCANFCD.HLP).

Table 1-1. Summary of Functions

Type of Function Name of Function Description

Initialization K_OpenDriver Initializes a Function Call Driver.

K_CloseDriver Closes a Function Call Driver. K_GetDevHandle Initializes a virtual board. K_FreeDevHandle Frees a device handle. K_DASDevInit Reinitializes a virtual board.

Operation K_ADRead Reads a single analog input value.

K_DMAStart Starts a DMA-mode operation. K_DMAStatus Gets the status of a DMA-mode operation. K_DMAStop Stops a DMA-mode operation. DASSCAN_EventEnable Enables the generation of a Windows event

(C/C++).

DASSCAN_EventDisable Disables the generation of a Windows event

(C/C++).

Frame management K_GetADFrame Accesses a frame for an analog input operation.

K_FreeFrame Frees a frame. K_ClearFrame Sets all frame elements to their default values.

1-4 Getting Started

Table 1-1. Summary of Functions (cont.)

Type of Function Name of Function Description

Memory management

Buffer address K_SetDMABuf Speciﬁes the address of a dynamically

Channel and gain K_SetChn Speciﬁes a single logical channel.

K_DMAAlloc Dynamically allocates a memory buffer for a

DMA-mode operation.

K_DMAFree Frees a memory buffer that was dynamically

allocated for a DMA-mode operation.

K_MoveBufToArray Transfers data from a dynamically allocated

memory buffer to a local array (Visual Basic for Windows).

allocated memory buffer.

K_SetStartStopChn Speciﬁes the ﬁrst and last logical channels in a

group of consecutive logical channels.

K_SetG Speciﬁes the gain for a group of consecutive

logical channels.

K_SetStartStopG Speciﬁes the ﬁrst and last logical channels in a

group of consecutive logical channels and the gain for all channels in the group.

K_SetChnGAry Speciﬁes the starting address of a channel-gain

queue.

K_FormatChnGAry Converts the format of a channel-gain queue

(Visual Basic for Windows).

K_RestoreChnGAry Restores a converted channel-gain queue

(Visual Basic for Windows).

K_SetADMode Speciﬁes the input range type (bipolar or

unipolar).

K_GetADMode Gets the input range type (bipolar or unipolar).

Clock K_SetClk Speciﬁes the pacer clock source.

K_SetClkRate Speciﬁes the clock rate for the internal pacer

clock. K_GetClkRate Gets the clock rate for the internal pacer clock. K_SetExtClkEdge Speciﬁes the active edge of an external pacer

clock.

Summary of Functions 1-5

Table 1-1. Summary of Functions (cont.)

Type of Function Name of Function Description

Trigger K_SetTrig Speciﬁes the trigger source.

K_SetDITrig Sets up a digital start trigger.

Gate K_SetGate Speciﬁes the status of a hardware gate. Miscellaneous K_GetErrMsg Gets the address of an error message string

(C/C++). K_GetVer Gets revision numbers. K_GetShellVer Gets the current DAS shell version.

Programming Flow Diagrams

This section contains a series of programming ﬂow diagrams illustrating the procedures you will typically follow when programming a D AS-Scan system using the DAS-Scan Function Call Driver. For more detailed information about the programming procedures, refer to the DAS-Scan Function Call Driver online help ﬁle (SCANFCD.HLP).

Although error checking is not shown in the ﬂow diagrams, it is recommended that you check the error/status code returned by each function used in your application program.

1-6 Getting Started

Preliminary Steps for All Analog Input Operations

Install all required ﬁles,

including the function and

variable type deﬁnition ﬁle

Declare and initialize program

variables

Initialize the driver

(K_OpenDriver)

Initialize a virtual board

(K_GetDevHandle)

Using another virtual board?

Perform the steps appropriate to your

operation (see the operation-speciﬁc

ﬂow diagrams)

Yes

Programming Flow Diagrams 1-7

Steps for a Single-Mode Analog Input Operation

Declare a variable in which

to store a single analog

input value

Read the count value

(K_ADRead)

Convert the count value

to voltage or degrees

Operation complete

1-8 Getting Started

Steps for a DMA-Mode Analog Input Operation

Access a frame for a virtual board

(K_GetADFrame)

Allocate a buffer

(K_DMAAlloc)

Specify the starting address

of the buffer

(K_SetDMABuf)

Continued on next page

Programming Flow Diagrams 1-9

Steps for a DMA-Mode Analog Input Operation (cont.)

Continued from previous page

Using a

channel-

gain

Using a

group of

consecutive

channels?

Yes

Specify the starting address

of the channel-gain queue

Deﬁne the

channel-gain

queue

Using

Visual

Basic?

(K_SetChnGAry)

Yes

Specify the ﬁrst and last channels

and the gain for all channels

K_SetStartStopChn and K_SetG)

Yes

(K_SetStartStopG or

Format the

channel-gain queue

(K_FormatChnGAry)

Modify the

channel-

gain

queue?

Yes

Restore the

channel-gain queue

(K_RestoreChnGAry)

Specify a single channel

(K_SetChn)

Specify the gain

for the single channel

(K_SetG)

Continued on next page

1-10 Getting Started

Steps for a DMA-Mode Analog Input Operation (cont.)

Continued from previous page

Specify the clock source

(K_SetClk)

Using

internal

clock?

Specify the external clock edge

(K_SetExtClkEdge)

Using an

external

digital start

trigger?

Specify an internal start trigger

(K_SetTrig)

Using a

hardware

gate?

Yes

Set the clock rate

(K_SetClkRate)

Specify an external start trigger

(K_SetTrig)

Specify digital

trigger conditions

(K_SetDITrig)

Specify the gate polarity

(K_SetGate)

Disable the gate

(K_SetGate)

Continued on next page

Programming Flow Diagrams 1-11

Steps for a DMA-Mode Analog Input Operation (cont.)

Continued from previous page

Setting up

another

virtual board?

Start the DMA-mode operation

(K_DMAStart)

Monitor the status of the operation

(K_DMAStatus)

Scanning

another

virtual board?

Yes

Access a frame for the virtual board;

go to the top of page 1-9

Continued on next page

1-12 Getting Started

Steps for a DMA-Mode Analog Input Operation (cont.)

Continued from previous page

Using Visual

Basic?

Read data

from each buffer

Convert data

from each buffer

Free each buffer

(K_DMAFree)

Free each frame

Yes

Transfer data from each

buffer to a local array (K_MoveBufToArray)

Read data

from each array

Convert data

from each array

Operation complete

Programming Flow Diagrams 1-13

Getting Help

If you need help installing or using the DAS-Scan Function Call Driver, call your local sales ofﬁce or call the following number for technical support:

(508) 880-3000 Monday - Friday, 8:00

An applications engineer will help you diagnose and resolve your problem over the telephone. Please make sure that you hav e the follo wing information available before you call:

SCAN-AD-HR board conﬁguration

SCAN-BRD assembly conﬁguration

A.M.

- 6:00

Serial # Revision code Base address setting Interrupt level setting DMA channel(s) External clock, trigger, or gate

Model Serial # Revision code Address setting (0h to 3Fh) Unipolar or bipolar mode

P.M.

, Eastern Time

_______________________ _______________________ _______________________ _______________________ _______________________ _______________________

_______________________ _______________________ _______________________ _______________________ _______________________

SCAN-BRD assembly conﬁguration

1-14 Getting Started

Model Serial # Revision code Address setting (0h to 3Fh) Unipolar or bipolar mode

_______________________ _______________________ _______________________ _______________________ _______________________

SCAN-BRD assembly conﬁguration

Model Serial # Revision code Address setting (0h to 3Fh) Unipolar or bipolar mode

_______________________ _______________________ _______________________ _______________________ _______________________

SCAN-BRD assembly conﬁguration

Getting Help 1-15

Model Serial # Revision code Address setting (0h to 3Fh) Unipolar or bipolar mode

_______________________ _______________________ _______________________ _______________________ _______________________

SCAN-BRD assembly conﬁguration

Model Serial # Revision code Address setting (0h to 3Fh) Unipolar or bipolar mode

_______________________ _______________________ _______________________ _______________________ _______________________

Computer

Operating system Compiler

1-16 Getting Started

Manufacturer CPU type Clock speed (MHz) KB of RAM Video system BIOS type

Windows version _______________________ Language

Manufacturer Version

_______________________ _______________________ _______________________ _______________________ _______________________ _______________________

_______________________ _______________________ _______________________

Available Operations

This chapter contains conceptual information about the DAS-Scan Function Call Driver functions typically used when programming a DAS-Scan system. It includes the following sections:

●

System Operations - information on initializing the Function Call

Driver, initializing a virtual board, generating a Windows event, retrieving revision levels, and handling errors.

●

Analog Input Operations - information on operation modes,

accessing a frame, memory allocation and management, gains, channels, the pacer clock, and triggers.

System Operations

This section describes the miscellaneous operations and general maintenance operations that apply to the entire DAS-Scan system and to the DAS-Scan Function Call Driver. It includes information on initializing the Function Call Driver, initializing a virtual board, generating a Windows event, retrieving revision levels, and handling errors.

Initializing the Driver

You must initialize the DAS-Scan Function Call Driver and any other Keithley DAS Function Call Drivers you are using in your application program. To initialize the drivers, use the K_OpenDriver function. Specify the driver you are using and the conﬁguration ﬁle that deﬁnes the use of the driver. The driver returns a unique identiﬁer for the driver; this identiﬁer is called the driver handle.

System Operations 2-1

You can specify a maximum of 30 driver handles for all the Keithley MetraByte drivers initialized from all your application programs. If you no longer require a driver and you want to free some memory or if you have used all 30 driv er handles, use the K_CloseDriver function to free a driver handle and close the associated driver.

If the driver handle you free is the last driver handle speciﬁed for a Function Call Driver, the driver is shut down. The DLLs associated with the Function Call Driver are shut down and unloaded from memory.

Initializing a Board

Each DAS-Scan system contains one physical SCAN-AD-HR board that you plug into your computer. You can attach up to 64 physical SCAN-BRD assemblies to the SCAN-AD-HR. Each SCAN-BRD assembly contains 64 physical channels.

The DAS-Scan Function Call Driver treats each group of four SCAN-BRD assemblies as a virtual board. Each virtual board contains 256 logical channels (four SCAN-BRD assemblies multiplied by 64 physical channels on each). Refer to page 2-12 for information on how the logical channels map to the virtual board.

The driver supports 16 virtual boards for a total of 4,096 logical channels (16 virtual boards multiplied by 256 logical channels on each). You must use the K_GetDevHandle function to initialize each virtual board you want to use. Specify the driver handle and the virtual board number (0 to

15). K_GetDevHandle veriﬁes that the SCAN-AD-HR board is present at the base address speciﬁed in the conﬁguration ﬁle, stops any operations currently in progress, initializes the SCAN-AD-HR board to its default state, and calibrates the analog-to-digital converter on the SCAN-AD-HR board.

K_GetDevHandle returns a unique identiﬁer for each virtual board; this

identiﬁer is called the device handle. Device handles allow you to communicate with more than one virtual board. Use the device handle returned by K_GetDevHandle in subsequent function calls related to the virtual board.

You can specify a maximum of 30 device handles for all the Keithley DAS products accessed from all your application programs. If you are no longer using a Keithley DAS product and you want to free some memory

2-2 Available Operations

or if you have used all 30 device handles, use the K_FreeDevHandle function to free a device handle.

Use K_GetDevHandle the ﬁrst time you initialize a board only. To reinitialize a virtual board after you have called K_GetDevHandle , use the K_DASDevInit function.

Generating a Windows Event

If you are performing a DMA-mode operation and programming in C/C++, you can program your DAS-Scan system to generate an interrupt when the operation stops (either because the speciﬁed number of samples was read or because an error, such as an o verﬂo w, occurred). You can then use the interrupt to generate a Windows event.

By default, the generation of Windows events is disabled. Use the

DASSCAN_EventEnable function to enable the generation of Windows

events. When an interrupt is generated, a Windows event is generated and a message is sent to your application program. Your application program can then take the appropriate action. Use the DASSCAN_EventDisable function to disable the generation of Windows events.

Notes:

DASSCAN_EventDisable ) before closing your application program.

The DAS-Scan Function Call Driver does not support the generation of Windows events when programming in Visual Basic for Windows.

If a Windows event is generated, the wParam parameter of the message structure speciﬁes the status of the operation as returned in the pStatus variable of K_DMAStatus . Refer to the DAS-Scan Function Call Driver online help ﬁle (SCANFCD.HLP) for more information about

K_DMAStatus .

You can generate a Windows event only if you are performing an operation in single-cycle buffering mode (the default buffering mode). If you change the buffering mode to continuous mode, the generation of Windows events is no longer supported. Refer to page 3-23 for information on when you can use continuous buffering mode.

Always disable the generation of Windows events (using

System Operations 2-3

Retrieving Revision Levels

If you are using functions from different Keithley DAS Function Call Drivers in the same application program or if you are having problems with your application program, you may want to verify which versions of the Function Call Driver, Keithley DAS Driver Speciﬁcation, and Keithley DAS Shell are used by the DAS-Scan system.

The K_GetVer function allows you to get both the revision number of the DAS-Scan Function Call Driver and the revision number of the Keithley DAS Driver Speciﬁcation to which the driver conforms.

The K_GetShellVer function allows you to get the revision number of the Keithley DAS Shell (the Keithley DAS Shell is a group of functions that are shared by all Keithley DAS products).

Handling Errors

Each FCD function returns a code indicating the status of the function. To ensure that your application program runs successfully, it is recommended that you check the returned code after the execution of each function. If the status code equals 0, the function executed successfully and your program can proceed. If the status code does not equal 0, an error occurred; ensure that your application program takes the appropriate action. Refer to the DAS-Scan Function Call Driver online help ﬁle (SCANFCD.HLP) for a complete list of error codes.

Each supported programming language uses a different procedure for error checking. Refer to the DAS-Scan Function Call Driver online help ﬁle (SCANFCD.HLP) for language-speciﬁc information.

For C/C++ application programs only, the DAS-Scan Function Call Driver provides the K_GetErrMsg function, which gets the address of the string corresponding to an error code.

2-4 Available Operations

Analog Input Operations

This section describes analog input operations. It includes information on the operation modes available, ho w to access a frame, ho w to allocate and manage memory, and how to specify channels and gains, the pacer clock source, and the trigger source for an analog input operation.

Operation Modes

The operation mode determines which attributes you can specify for an analog input operation and how data is transferred from the SCAN-AD-HR board to computer memory . Y ou can perform analog input operations in single mode or DMA mode, as described in the following sections.

Single Mode

DMA Mode

In single mode, the SCAN-AD-HR board acquires a single sample from a single logical channel. The driver initiates the conversion; you cannot perform any other operation until the single-mode operation is complete.

Use the K_ADRead function to perform an analog input operation in single mode. You specify the virtual board that the logical channel is associated with, the logical channel, the gain at which you want to read the signal, and the variable in which to store the converted data.

The data in the variable is stored as a count value. Refer to Appendix A for information on converting the count value to voltage or degrees.

DMA mode is the recommended way to transfer data. In DMA mode, the SCAN-AD-HR board acquires a single sample or multiple samples from one or more logical channels (up to a maximum of 256) on the same virtual board. A hardware clock initiates conversions. Once the analog input operation begins, control returns to your application program. The hardware temporarily stores the acquired data in the FIFO (ﬁrst-in, ﬁrst-out data buffer) on the SCAN-AD-HR board and then transfers the data to a user-deﬁned DMA buffer in the computer.

Analog Input Operations 2-5

Use the K_DMAStart function to start the DMA-mode operation on the ﬁrst virtual board, specifying the handle of the frame that deﬁnes the ﬁrst operation. After the SCAN-AD-HR board reads a sample from each logical channel associated with the virtual board and stores the samples in the user-deﬁned buffer, the operation stops. (Use the K_DMAStatus function to monitor the status of the operation and determine when the operation stops.) Then, use K_DMAStart again to start the DMA-mode operation on the next virtual board, specifying the handle of the frame that deﬁnes the next operation.

Refer to page 1-9 for the procedure to follow when performing a DMA-mode operation. In addition, example programs 1 and 3, provided in the ASO-SCAN software package, illustrate how to acquire data in DMA mode.

The data in the user-deﬁned DMA buffer is stored as count values. Refer to Appendix A for information on con v erting the count v alue to voltage or degrees.

Notes:

Because of the overhead required to stop one DMA-mode operation and start another, a slight delay occurs before the DAS-Scan system begins acquiring data on each subsequent virtual board.

If DMA resources are not available, you can also perform an analog input operation in interrupt mode, using interrupts to indicate when data should be transferred from the FIFO. Refer to page 3-19 for more information.

Typically, you want the operation to stop automatically after one sample from each logical channel on the virtual board has been read; this is referred to as single-cycle buffering mode. However, if you are acquiring data from 256 logical channels or fewer, you can also use continuous buffering mode; this allo ws you to continuously acquire data, o verwriting any values already stored in memory. Refer to page 3-23 for more information.

You can perform an analog input operation in single-DMA mode or dual-DMA mode, depending on whether you speciﬁed one or two DMA channels in your conﬁguration ﬁle. Refer to the DAS-Scan User’s Guide for more information.

2-6 Available Operations

Accessing a Frame

A frame is a data structure whose elements deﬁne the attributes of a DMA-mode analog input operation. For each virtual board in your DAS-Scan system, use the K_GetADFrame function to access an A/D (analog-to-digital) frame. The driver returns a unique identiﬁer for each frame; this identiﬁer is called the frame handle.

Specify the attributes of each operation by using a separate setup function to deﬁne each element of the A/D frame. Use the frame handle returned by the driver in each setup function to ensure that you always deﬁne the operation for the same virtual board. For example, assume that you access an A/D frame with the frame handle ADFrame1. To specify the logical channel on which to perform the operation, use the K_SetChn setup function, referencing the frame handle ADFrame1; to specify the gain at which to read the logical channel, use the K_SetG setup function, also referencing the frame handle ADFrame1.

When you are ready to perform the operation you set up, use the

K_DMAStart function to start the operation, again referencing the

appropriate frame handle. Figure 2-1 illustrates the use of an A/D frame where the frame handle is ADFrame1.

K_DMAStart (ADFrame1)

ADFrame1

Start Channel Stop Channel Clock Source Trigger Source

. . .

Figure 2-1. Frame-Based Operation

Attributes of Operation

First analog input channel Last analog input channel Pacer clock source Trigger source

. . .

Analog Input Operations 2-7

Frames help you create structured application programs. They are useful for operations that have many deﬁning attributes, since providing a separate argument for each attribute could make a function’ s ar gument list unmanageably long. In addition, some attributes, such as the clock source and trigger source, are only available for operations that use frames.

You must use as least as many frames as you have virtual boards. For example, if you are using 16 virtual boards (the maximum number), you must use at least 16 frames. The maximum number of frames that you can use in your application program is 32 (two for each virtual board).

Note:

To acquire data from all the virtual boards in your DAS-Scan system as smoothly as possible, make sure that you deﬁne the elements of each frame consistently . For e xample, to use the same pacer clock rate for all the virtual boards in your DAS-Scan system, specify the same number of clock ticks for each frame.

If you want to perform a DMA-mode operation on a virtual board and all frames have been accessed, use the K_FreeFrame function to free a frame that is no longer in use. You can then redeﬁne the elements of the frame for the next operation.

When you access a frame, the elements are set to their default values. You can also use the K_ClearFrame function to reset all the elements of a frame to their default values.

Table 2-1 lists the elements of an A/D frame that are typically deﬁned for a DAS-Scan system. This table also lists the default value of each element, the setup functions used to deﬁne each element, and the page(s) in this manual on which to ﬁnd additional information. Refer to the DAS-Scan Function Call Driver online help ﬁle (SCANFCD.HLP) for more detailed information about the setup functions.

2-8 Available Operations

Table 2-1. A/D Frame Elements

Element Default Value Setup Function Page Number

Buffer Number of Samples 0 K_SetDMABuf page 2-9 Start Channel 0 K_SetChn page 2-17

Stop Channel 0 K_SetStartStopChn page 2-17

Gain 0 (gain of 1) K_SetG page 2-17

0 (NULL) K_SetDMABuf page 2-9

K_SetStartStopChn page 2-17 K_SetStartStopG page 2-17

K_SetStartStopG page 2-17

K_SetStartStopG page 2-17 Channel-Gain Queue 0 (NULL) K_SetChnGAry page 2-18 Clock Source Internal K_SetClk page 2-20, page 2-21 Pacer Clock Rate External Clock Edge Negative K_SetExtClkEdge page 2-21 Trigger Source Internal K_SetTrig page 2-23 Trigger Polarity Positive K_SetDITrig page 2-23 Hardware Gate Disabled K_SetGate page 2-24

Notes

This element must be set.

0 K_SetClkRate page 2-20

Memory Allocation and Management

A DMA-mode analog input operation requires memory in which to store the acquired data.

To reserve memory, use the K_DMAAlloc function to dynamically allocate a memory buffer for each virtual board. Specify the number of samples to store in the buffer (typically, one sample for each logical channel associated with the virtual board). The driver returns the starting

Analog Input Operations 2-9

address of the buffer and a unique identiﬁer for the buffer (this identiﬁer is called the memory handle).

When you no longer require the buffer , you can free the b uf fer for another use by specifying the memory handle in the K_DMAFree function.

After you allocate your buffer, use the K_SetDMABuf function to assign the starting address of the buffer and the number of samples to store in the buffer.

Notes:

For Visual Basic for Windows, data in a dynamically allocated

buffer is not directly accessible to your program. You must use the

K_MoveBufToArray function to move the data from the dynamically

allocated buffer to the program’s local array.

If you are writing Windows 95, 32-bit programs, you must install the Keithley Memory Manager. Refer to your board user’s guide for information.

Typically, a single buffer that can hold one sample for each logical channel associated with the virtual board is sufﬁcient. Howe ver , if you are acquiring data from 256 logical channels or fewer , you can also allocate a larger buffer or multiple buffers, allowing you to sample each logical channel multiple times. Refer to page 3-24 for more information.

The area used for dynamically allocated memory buffers is referred to as the global heap. This area of memory is left unoccupied as your application program and other programs run. The K_DMAAlloc function calls the GlobalAlloc API function to allocate the desired buffer size from the global heap. Dynamically allocated memory is guaranteed to be ﬁxed and locked in memory.

To eliminate page wrap conditions and to guarantee that dynamically allocated memory is suitable for use by the computer’s 8237 DMA controller, K_DMAAlloc may allocate an area twice as large as actually needed. Once the data in this buffer is processed and/or saved elsewhere, use K_DMAFree to free the memory for other uses.

2-10 Available Operations

Gains

Each logical channel of your DAS-Scan system can measure analog input signals in one of eight, software-selectable unipolar or bipolar analog input ranges. You initially set the input range type (unipolar or bipolar) for each virtual board in your conﬁguration ﬁle; refer to the DAS-Scan User’ s

Guide for more information. To reset the input range type for a virtual

board in your application program, use the K_SetADMode function.

T able 2-2 lists the analog input ranges supported by the D AS-Scan system and the gain and gain code associated with each range. (The gain code is used by the Function Call Driver to represent the gain.)

Table 2-2. Analog Input Ranges

Analog Input Range

Gain

±10 V 0 to 10 V 1 0 ±5 V 0 to 5 V 2 1 ±2.5 V 0 to 2.5 V 4 2 ±1.25 V 0 to 1.25 V 8 3 ±0.2 V 0 to 0.2 V 50 4 ±0.1 V 0 to 0.1 V 100 5 ±50 mV 0 to 50 mV 200 6 ±25 mV 0 to 25 mV 400 7

CodeBipolar Unipolar

For a single-mode operation, you specify the gain code in the

K_ADRead function.

For a DMA-mode operation, you specify the gain code in the K_SetG or

K_SetStartStopG function; the function you use depends on how you

specify the logical channels, as described in the following section.

Analog Input Operations 2-11

Channels

A DAS-Scan system can contain a maximum of 4,096 analog input channels. You can perform an analog input operation on a single channel or on a group of multiple channels called a scan. The following sections describe how to address and specify the channels you are using.

Addressing Channels

As mentioned previously, each DAS-Scan system contains one physical SCAN-AD-HR board that you plug into your computer. You can attach up to 64 physical SCAN-BRD assemblies to the SCAN-AD-HR. You give each SCAN-BRD assembly a unique address (from 0h to 3Fh, 0 to 63 decimal) by setting a thumbwheel on the board. Each SCAN-BRD assembly contains 64 physical channels, numbered from 0 to 63 on each assembly.

The DAS-Scan Function Call Driver treats each group of four SCAN-BRD assemblies as a virtual board. Because duplicate physical channel numbers can be associated with a virtual board, the driver uses a logical channel number (from 0 to 255) to uniquely identify each physical channel . The channel number that you specify in Function Call Driver functions is always a logical channel number.

Table 2-3 illustrates the mapping of logical channels to virtual boards for the maximum conﬁguration of 4,096 channels. Table 2-3 assumes that when you set the address thumbwheels on the SCAN-BRD assemblies and speciﬁed the addresses in the conﬁguration ﬁle, you assigned the SCAN-BRD assemblies sequential addresses, as recommended. However, you can assign any address to any SCAN-BRD assembly, as long as no two SCAN-BRD assemblies have the same address.

2-12 Available Operations

Table 2-3. Virtual Boards and Logical Channels

Virtual Board SCAN-BRD Assemblies

0 SCAN-BRD0 (Address 0h) 0 to 63

SCAN-BRD1 (Address 1h) 64 to 127 SCAN-BRD2 (Address 2h) 128 to 191 SCAN-BRD3 (Address 3h) 192 to 255

1 SCAN-BRD0 (Address 4h) 0 to 63

SCAN-BRD1 (Address 5h) 64 to 127 SCAN-BRD2 (Address 6h) 128 to 191 SCAN-BRD3 (Address 7h) 192 to 255

2 SCAN-BRD0 (Address 8h) 0 to 63

SCAN-BRD1 (Address 9h) 64 to 127 SCAN-BRD2 (Address Ah) 128 to 191 SCAN-BRD3 (Address Bh) 192 to 255

3 SCAN-BRD0 (Address Ch) 0 to 63

SCAN-BRD1 (Address Dh) 64 to 127

Logical Channels

SCAN-BRD2 (Address Eh) 128 to 191 SCAN-BRD3 (Address Fh) 192 to 255

4 SCAN-BRD0 (Address 10h) 0 to 63

SCAN-BRD1 (Address 11h) 64 to 127 SCAN-BRD2 (Address 12h) 128 to 191 SCAN-BRD3 (Address 13h) 192 to 255

5 SCAN-BRD0 (Address 14h) 0 to 63

SCAN-BRD1 (Address 15h) 64 to 127 SCAN-BRD2 (Address 16h) 128 to 191 SCAN-BRD3 (Address 17h) 192 to 255

Analog Input Operations 2-13

Table 2-3. Virtual Boards and Logical Channels (cont.)

Virtual Board SCAN-BRD Assemblies

6 SCAN-BRD0 (Address 18h) 0 to 63

SCAN-BRD1 (Address 19h) 64 to 127 SCAN-BRD2 (Address 1Ah) 128 to 191 SCAN-BRD3 (Address 1Bh) 192 to 255

7 SCAN-BRD0 (Address 1Ch) 0 to 63

SCAN-BRD1 (Address 1Dh) 64 to 127 SCAN-BRD2 (Address 1Eh) 128 to 191 SCAN-BRD3 (Address 1Fh) 192 to 255

8 SCAN-BRD0 (Address 20h) 0 to 63

SCAN-BRD1 (Address 21h) 64 to 127 SCAN-BRD2 (Address 22h) 128 to 191 SCAN-BRD3 (Address 23h) 192 to 255

9 SCAN-BRD0 (Address 24h) 0 to 63

SCAN-BRD1 (Address 25h) 64 to 127

Logical Channels

SCAN-BRD2 (Address 26h) 128 to 191 SCAN-BRD3 (Address 27h) 192 to 255

10 SCAN-BRD0 (Address 28h) 0 to 63

SCAN-BRD1 (Address 29h) 64 to 127 SCAN-BRD2 (Address 2Ah) 128 to 191 SCAN-BRD3 (Address 2Bh) 192 to 255

11 SCAN-BRD0 (Address 2Ch) 0 to 63

SCAN-BRD1 (Address 2Dh) 64 to 127 SCAN-BRD2 (Address 2Eh) 128 to 191 SCAN-BRD3 (Address 2Fh) 192 to 255

2-14 Available Operations

Table 2-3. Virtual Boards and Logical Channels (cont.)

Virtual Board SCAN-BRD Assemblies

12 SCAN-BRD0 (Address 30h) 0 to 63

SCAN-BRD1 (Address 31h) 64 to 127 SCAN-BRD2 (Address 32h) 128 to 191 SCAN-BRD3 (Address 33h) 192 to 255

13 SCAN-BRD0 (Address 34h) 0 to 63

SCAN-BRD1 (Address 35h) 64 to 127 SCAN-BRD2 (Address 36h) 128 to 191 SCAN-BRD3 (Address 37h) 192 to 255

14 SCAN-BRD0 (Address 38h) 0 to 63

SCAN-BRD1 (Address 39h) 64 to 127 SCAN-BRD2 (Address 3Ah) 128 to 191 SCAN-BRD3 (Address 3Bh) 192 to 255

15 SCAN-BRD0 (Address 3Ch) 0 to 63

SCAN-BRD1 (Address 3Dh) 64 to 127

Logical Channels

SCAN-BRD2 (Address 3Eh) 128 to 191 SCAN-BRD3 (Address 3Fh) 192 to 255

For each virtual board, you can determine the logical channel number corresponding to a particular physical channel number by using the following equation:

LogicalChn# PhysicalChan# 64 SCAN-BRD#×()+=

Analog Input Operations 2-15

where

PhysicalChan# is an integer from 0 to 63 that indicates the physical channel number on the SCAN-BRD assembly speciﬁed by SCAN-BRD#, and

SCAN-BRD# is an integer from 0 to 3 that indicates on which SCAN-BRD assembly the physical channel is located (0 indicates the ﬁrst SCAN-BRD assembly associated with the virtual board, 1 indicates the second SCAN-BRD assembly associated with the virtual board, 2 indicates the third SCAN-BRD assembly associated with the virtual board, and 3 indicates the fourth SCAN-BRD assembly associated with the virtual board).

For example, the logical channel that identiﬁes physical channel 15 on SCAN-BRD2 (the third SCAN-BRD assembly associated with the virtual board) is determined as follows:

LogicalChan# 15 64 2×()+ 15 128+143===

By using a combination of the virtual board number and the logical channel number in software, you can uniquely identify each channel in your DAS-Scan system. For example, assume you have eight SCAN-BRD assemblies connected to your SCAN-AD-HR board. Physical channel number 51 on the fourth SCAN-BRD assembly (SCAN-BRD3, Address 3) is identiﬁed as virtual board 0, logical channel 243 (51 + (64 x 3)); physical channel 51 on the eighth SCAN-BRD assembly (SCAN-BRD3, Address 7) is identiﬁed as virtual board 1, logical channel 243.

Note: In the conﬁguration ﬁle, the SCAN-BRD assemblies are addressed

sequentially from 0h to 3Fh (0 to 63 decimal), as shown in Table 2-3. However, for the purposes of determining the logical channel number, always use the number of the SCAN-BRD assembly in relation to a virtual board (0, 1, 2, or 3).

2-16 Available Operations

Specifying a Single Channel

For a single-mode analog input operation, you can acquire a single sample from a single logical channel. Use the K_ADRead function to specify the virtual board, the logical channel, and the gain code.

For a DMA-mode analog input operation, you can acquire a single sample or multiple samples from a single logical channel. Use the K_SetChn function to specify the logical channel and the K_SetG function to specify the gain code.

Refer to Table 2-2 on page 2-11 for a list of the analog input ranges supported by the DAS-Scan system and the gain code associated with each range.

Note: If you are measuring steady-state signals, you can reduce the

effects of noise by performing a separate DMA-mode operation on each logical channel and then averaging the results of each operation. For example, you can perform one DMA-mode operation in which you acquire 1,000 samples from logical channel 0 at a gain of 1 and another DMA-mode operation in which you acquire 2,000 samples from logical channel 1 at a gain of 200.

Specifying a Group of Consecutive Logical Channels

For a DMA-mode analog input operation, you can acquire samples from a group of up to 256 consecutive logical channels associated with the same virtual board. Use the K_SetStartStopChn function to specify the ﬁrst and last logical channels. The channels are sampled in order from ﬁrst to last.

The ﬁrst logical channel can be higher than the last logical channel. For example, if the ﬁrst logical channel is 255 and the last logical channel is 2, your program reads data ﬁrst from logical channel 255, then from logical channels 0, 1, and 2.

Use the K_SetG function to specify the gain code for all logical channels in the group. (All logical channels must use the same gain code.) Use the K_SetStartStopG function to specify the gain code, the ﬁrst logical channel, and the last logical channel in a single function call.

Analog Input Operations 2-17

Refer to Table 2-2 on page 2-11 for a list of the analog input ranges supported by the DAS-Scan system and the gain code associated with each range.

Note: If you are measuring temperature with a SCAN-BRD-TC or

SCAN-BRD-TC-ISO assembly , you can use physical channels 31 and 63 as CJC sensors to measure the temperature of the screw terminals. If you enable a CJC channel, the CJC channel should be read at a gain of 1. Unless you intend to read all your channels at a gain of 1, you must either disable the CJC channels or specify your measurement channels in a channel-gain queue. Refer to the next section for information about channel-gain queues.

Specifying Channels in a Channel-Gain Queue

For a DMA-mode analog input operation, you can use a hardware channel-gain queue to acquire samples from up to 256 logical channels associated with the same virtual board. You specify the logical channels you want to sample, the order in which you want to sample them, and a gain code for each logical channel.

You can set up the logical channels in a channel-gain queue either in consecutive order or in nonconsecutive order. You can also specify the same logical channel more than once. The channels are sampled in order from the ﬁrst logical channel in the queue to the last logical channel in the queue.

Refer to Table 2-2 on page 2-11 for a list of the analog input ranges supported by the DAS-Scan system and the gain code associated with each range.

The way that you specify the logical channels and gains in a channel-gain queue depends on the language you are using. Refer to the DAS-Scan Function Call Driver online help ﬁle (SCANFCD.HLP) for language-speciﬁc information.

After you create the channel-gain queue in your program, use the K_SetChnGAry function to specify the staring address of the channel-gain queue.

2-18 Available Operations

Notes: The throughput of the DAS-Scan system is reduced when using a

channel-gain queue, particularly when the SCAN-AD-HR board must switch the gain between each logical channel. Therefore, it is recommended that you keep all logical channels you are reading at a particular gain together, even if you must arrange the channels out of sequence.

For example, assume that you are measuring temperature on a SCAN-BRD-TC or SCAN-BRD-TC-ISO assembly and you are using physical channels 31 and 63 as CJC sensors to measure the temperature of the screw terminals. Since the CJC channels should be read at a gain of 1, arrange the channel-gain queue so that you read all the measurement channels ﬁrst and then read the CJC channels. Example program 4, provided in the ASO-SCAN software package, illustrates the use of a channel-gain queue with the CJC channels enabled.

If you are not using all 256 logical channels on a virtual board, you can allow for settling time by specifying the same logical channel twice and then ignoring the reading from the ﬁrst logical channel.

If you are not using all 256 logical channels on a virtual board, you can reduce the effects of noise by specifying the same logical channel multiple times and then averaging the readings from each channel. For example, you can specify logical channel 0 for the ﬁrst ﬁve entries in the channel-gain queue, logical channel 1 for the next ﬁve entries, and so on.

Pacer Clock

For a DMA-mode operation, you can use a pacer clock to determine the period between the conversion of one logical channel and the conversion of the next logical channel in a scan of multiple logical channels. You can specify an internal or an external pacer clock, as described in the following sections.

Analog Input Operations 2-19

Notes: The rate at which the computer can reliably read data from the

SCAN-AD-HR board depends on a number of factors, including your computer, the operating system/environment, the types of SCAN-BRD assemblies you are using, the gains of the channels, and other software issues. If your data appears to be invalid, you may have to use a slower clock rate. Refer to the DAS-Scan User’s Guide for the maximum throughput rates supported for each SCAN-BRD assembly at each gain.

T ypically, using the pacer clock to control the period between conversions of individual logical channels in a scan is sufﬁcient; this is referred to as paced conversion mode. However, if you are acquiring data from 256 logical channels or fewer , you can use both the pacer clock (to control the period between individual logical channels in a scan) and the burst mode conversion clock (to control the period between conversions of the entire scan); this is referred to as burst conversion mode. Refer to page 3-25 for more information about specifying burst conversion mode. Refer to page 3-26 for more information about using the burst mode conversion clock.

Internal Pacer Clock

The internal pacer clock uses two cascaded counters of the counter/timer circuitry on the SCAN-AD-HR board. The counters are normally in an idle state. When you start the analog input operation (using K_DMAStart), a conversion is initiated. Note that a slight time delay occurs between the time the operation is started and the time the conversion is initiated.

After the ﬁrst conversion is initiated, the counters are loaded with a count value and begin counting down. When the counters count down to 0, another conversion is initiated and the process repeats.

Because the counters use a 5 MHz time base, each count represents

0.2

µs. Use the K_SetClkRate function to specify the number of counts

(clock ticks) between conversions. For example, if you specify a count of 300, the period between conversions is 60

µs (16.67 ksamples/s); if you

specify a count of 87,654, the period between conversions is 17.53 ms (57 samples/s).

2-20 Available Operations

You can specify a count value from 50 (100 kHz) to 4,294,836,255 (0.0012 Hz). The period between conversions ranges from 10

µs to

14.3 minutes.

When using an internal pacer clock, use the following formula to determine the number of counts to specify:

For example, if you want a conversion rate of 10 ksamples/s, specify a count of 500, as shown in the following equation:

If you want to use the same conversion rate for all the virtual boards in your DAS-Scan system, call K_SetClkRate once for each virtual board and specify the same number of counts for each.

The internal pacer clock is the default pacer clock. To reset the pacer clock source to the internal pacer clock, use the K_SetClk function. (If you want to reset all the virtual boards in your DAS-Scan system to use the internal pacer clock, call K_SetClk once for each virtual board and specify the internal pacer clock for each.)

External Pacer Clock

You connect an external pacer clock to the J5 connector on the SCAN-AD-HR board. When you start an analog input operation (using K_DMAStart), conversions are armed. At the next active edge of the external pacer clock (and at every subsequent active edge of the external pacer clock), a conversion is initiated.

counts

5 000 000,,

-------------------------- -500=

10 000,

5 MHz time base

---------------------------------------- -= conversion rate

Use the K_SetClk function to specify an external pacer clock. Then, use the K_SetExtClkEdge function to specify the active edge (rising or falling) of the external pacer clock. A falling edge is the default active edge.

If you are using an external pacer clock, make sure that the clock initiates conversions at a rate that the analog-to-digital converter can handle.

Analog Input Operations 2-21

Triggers

If you want to use an external pacer clock source for all the virtual boards in your DAS-Scan system, call K_SetClk once for each virtual board and specify an external pacer clock for each. If you want to use the same active edge for all the virtual boards in your DAS-Scan system, call

K_SetExtClkEdge once for each virtual board and specify the same

active edge for each.

Note:

You cannot use an external pacer clock if you are using either an

external digital trigger or a hardware gate.

A trigger is an event that occurs based on a speciﬁed set of conditions. If you are performing DMA-mode analog input operations on a series of virtual boards, you can specify a start trigger for the ﬁrst virtual board to determine when acquisitions start.

The start trigger can be an internal trigger or an external digital trigger, as described in the following sections.

The trigger event is not signiﬁcant until the operation has been started (using K_DMAStart ). The point at which conversions begin relative to the trigger event depends on the pacer clock; refer to page 2-19 for more information.

Note:

this is referred to as post-trigger acquisition. However, if you are performing a DMA-mode operation and acquiring data from 256 logical channels or fewer, you can also use an optional second trigger, the about trigger, to acquire data before the trigger event occurs (referred to as pre-trigger acquisition) or both before and after the trigger event occurs (referred to as about-trigger acquisition). Refer to page 3-26 for more information about specifying pre-trigger acquisition. Refer to page 3-28 for more information about specifying about-trigger acquisition.

2-22 Available Operations

Typically, you want to acquire data after the trigger event occurs;

Internal T rigger

An internal trigger is a software trigger. The trigger event occurs when you start the operation. Note that a slight delay occurs between the time you start the operation and the time the trigger event occurs.

If you want to use an internal start trigger, specify an internal trigger for all the virtual boards in your DAS-Scan system.

The internal trigger is the default trigger source. To reset the trigger source to an internal trigger, use the K_SetTrig function.

External Digital Trigger

An external digital trigger event occurs when an active edge is detected on the digital trigger signal connected to the J5 connector on the SCAN-AD-HR board.

Use the K_SetTrig function to specify an external trigger. Then, use the

K_SetDITrig function to specify whether you want the trigger event to

occur on a rising edge (positive-edge trigger) or on a falling edge (negative-edge trigger). The trigger conditions are illustrated in Figure 2-2.

Negative-edge

trigger event occurs Positive-edge trigger event occurs

Trigger signal

Figure 2-2. Digital Trigger Conditions

If you want to use an external digital start trigger, specify an external trigger (using K_SetTrig ) and call K_SetDITrig for the ﬁrst virtual board only. For all subsequent virtual boards, use K_SetTrig to specify an internal trigger and do not call K_SetDITrig .

Analog Input Operations 2-23

Note:

external pacer clock or a hardware gate.

Hardware Gate

A hardware gate is an externally applied digital signal that determines when conversions can occur. You connect the gate signal to the J5 connector on the SCAN-AD-HR board.

If you start a DMA-mode analog input operation (using K_DMAStart ) and the hardware gate is enabled, the state of the gate signal determines whether conversions occur, as follows:

●

Use the K_SetGate function to enable and disable a hardware gate and to specify the gate polarity (positive or negative).

You cannot use an external digital trigger if you are using either an

If you specify a positive gate, conversions occur only if the signal to the J5 connector is high; if the signal to the J5 connector is low, conversions are inhibited.

If you specify a negative gate, conversions occur only if the signal to the J5 connector is low; if the signal to the J5 connector is high, conversions are inhibited.

If you want to use a hardware gate for all the virtual boards in your DAS-Scan system, call K_SetGate once for each virtual board and specify the same polarity for each.

The default state of the hardware gate is disabled. If you enable a hardware gate for all the virtual boards in your DAS-Scan system and later want to disable the hardware gate, call K_SetGate once for each virtual board and specify disabled for each.

You cannot use a hardware gate if you are using either an external

Note:

pacer clock or an external digital trigger.

2-24 Available Operations

Additional Features

This chapter contains conceptual information about additional features of the DAS-Scan Function Call Driver. It includes the following sections:

Summary of Additional Functions - a brief description of the

●

additional DAS-Scan Function Call Dri v er functions that you can use when reading 256 logical channels or fewer or when performing an interrupt-mode analog input operation.

●

Additional Programming Flow Diagrams - an illustration of the

procedures to follow when using all of the DAS-Scan Function Call Driver functions.

●

Performing an Interrupt-Mode Operation - information on

performing an interrupt-mode analog input operation.

●

Specifying Continuous Mode - information on specifying

continuous buffering mode.

●

Reserving Large or Multiple Memory Buffers - information on

dynamically allocating a large memory buffer or dynamically allocating multiple memory buffers.

●

Specifying Burst Mode - information on specifying burst conv ersion

mode.

●

Using the Burst Mode Conversion Clock - information on using the

burst mode conversion clock to acquire data in burst mode.

●

Specifying Pre-T rigger Acquisition - information on using the about

trigger to acquire data before a trigger event occurs.

Specifying About-T rigger Acquisition - information on using the

●

about trigger to acquire data both before and after a trigger event occurs.

3-1

Summary of Additional Functions

Table 3-1 describes the additional functions in the DAS-Scan Function Call Driver that you can use when reading 256 logical channels or fewer or when performing an interrupt-mode analog input operation. For more detailed information about the functions, refer to the information in this chapter beginning on page 3-19 and to the DAS-Scan Function Call Driver online help ﬁle (SCANFCD.HLP).

Table 3-1. Summary of Additional Functions

Type of Function Name of Function Description

Operation K_IntStart Starts an interrupt-mode operation.

K_IntStatus Gets the status of an interrupt-mode operation. K_IntStop Stops an interrupt-mode operation.

Memory management

Buffer address K_SetBuf Speciﬁes a local array (C/C++) or a

Buffering mode K_SetContRun Speciﬁes continuous mode.

K_IntAlloc Dynamically allocates a memory buffer for an

interrupt-mode operation.

K_IntFree Frees a memory buffer that was dynamically

allocated for an interrupt-mode operation.

dynamically allocated memory buffer (C/C++ or Visual Basic for Windows) for an interrupt-mode operation.

K_SetBufI Speciﬁes a local array (Visual Basic for

Windows) for an interrupt-mode operation.

K_BufListAdd Adds a buffer or array to the list of multiple

buffers or arrays.

K_BufListReset Clears the list of multiple buffers or arrays.

K_ClrContRun Speciﬁes single-cycle mode.

Conversion mode K_SetADFreeRun Speciﬁes burst mode.

K_ClrADFreeRun Speciﬁes paced mode.

3-2 Additional Features

Table 3-1. Summary of Additional Functions (cont.)

Type of Function Name of Function Description

Clock K_SetBurstTicks Speciﬁes the burst mode conversion rate.

K_GetBurstTicks Gets the burst mode conversion rate.

Trigger K_SetAboutTrig Enables the about trigger and speciﬁes the

number of post-trigger samples.

K_ClrAboutTrig Disables the about trigger.

Additional Programming Flow Diagrams

This section contains a series of programming ﬂow diagrams illustrating the procedures to follow when using all of the DAS-Scan Function Call Driver functions. For more detailed information about the programming procedures, refer to the DAS-Scan Function Call Driver online help ﬁle (SCANFCD.HLP).

Although error checking is not shown in the ﬂow diagrams, it is recommended that you check the error/status code returned by each function used in your application program.

Additional Programming Flow Diagrams 3-3

Preliminary Steps for All Analog Input Operations

Install all required ﬁles, including the function and variable type deﬁnition ﬁle

Declare and initialize program

variables

Initialize the driver

(K_OpenDriver)

Initialize a virtual board

(K_GetDevHandle)

Using another virtual board?

Perform the steps appropriate to your

operation (see the operation-speciﬁc

ﬂow diagrams)

Yes

3-4 Additional Features

Steps for a Single-Mode Analog Input Operation

Declare a variable in which

to store a single analog

input value

Read the count value

(K_ADRead)

Convert the count value

to voltage or degrees

Operation complete

Additional Programming Flow Diagrams 3-5

Steps for an Interrupt-Mode Analog Input Operation

Access a frame for a virtual board

(K_GetADFrame)

Scanning

256 channels

or fewer?

Using a

dynamically

allocated

memory

buffer?

Declare and dimension

a local array

Specify the starting address of

the local array

(K_SetBuf for C/C++,

K_SetBufI for Visual Basic)

Yes

Using

multiple

buffers or

arrays?

Allocate a buffer

(K_IntAlloc)

Specify the

starting address

of the buffer

(K_SetBuf)

Yes

dynamically

allocated

Declare and

dimension

each local array

Add each array to the

list of multiple arrays

(K_BufListAdd)

Using

memory

buffers?

Yes

Allocate each buffer

Add each buffer

multiple buffers (K_BufListAdd)

(K_IntAlloc)

to the list of

Continued on next page

3-6 Additional Features

Steps for an Interrupt-Mode Analog Input Operation (cont.)

Continued from previous page

Using a

channel-

gain

Using a

group of

consecutive

channels?

Yes

Specify the starting address

of the channel-gain queue

Yes

Deﬁne the

channel-gain

queue

Using

Visual

Basic?

(K_SetChnGAry)

Yes

Specify the ﬁrst and last channels

and the gain for all channels

K_SetStartStopChn and K_SetG)

Format the

channel-gain queue

(K_FormatChnGAry)

Modify the

channel-

gain

queue?

(K_SetStartStopG or

Yes

Restore the

channel-gain queue

(K_RestoreChnGAry)

Specify a single channel

(K_SetChn)

Specify the gain

for the single channel

(K_SetG)

Continued on next page

Additional Programming Flow Diagrams 3-7

Steps for an Interrupt-Mode Analog Input Operation (cont.)

Continued from previous page

Specify the clock source

(K_SetClk)

Using

internal

clock?

Specify the external clock edge

(K_SetExtClkEdge)

Scanning

256 channels

or fewer?

Yes

Set the clock rate

(K_SetClkRate)

Using

paced

mode?

Specify burst conversion mode

(K_SetADFreeRun)

Set the burst mode conversion rate

(K_SetBurstTicks)

Yes

Specify paced conversion mode

(K_ClrADFreeRun)

Specify the buffering mode

(K_SetContRun for continuous mode,

K_ClrContRun for single-cycle mode)

Continued on next page

3-8 Additional Features

Steps for an Interrupt-Mode Analog Input Operation (cont.)

Continued from previous page

Using an

external

digital start

trigger?

Specify an internal

start trigger (K_SetTrig)

Using a

hardware

gate?

Disable the gate

(K_SetGate)

Yes

Specify an external start trigger

(K_SetTrig)

Specify the digital

trigger conditions

(K_SetDITrig)

Specify the gate polarity

(K_SetGate)

Setting up

another

virtual board?

Continued on next page

Yes

Access a frame for the virtual board;

go to the top of page 3-6

Additional Programming Flow Diagrams 3-9

Steps for an Interrupt-Mode Analog Input Operation (cont.)

Continued from previous page

Start the interrupt-mode operation

(K_IntStart)

Monitor the status of the operation

(K_IntStatus)

Scanning

256 channels

or fewer?

Scanning

another

virtual

board?

Continued on next page

Yes

Using

continuous

buffering

mode?

Yes

Stop the operation

(K_IntStop)

3-10 Additional Features

Steps for an Interrupt-Mode Analog Input Operation (cont.)

Continued from previous page

Using

dynamically

allocated

buffers?

Read data

from each array

Convert data

from each array

Scanning

256 channels

or fewer?

Yes

Using

Visual

Basic?

Read data

from each buffer

Convert data

from each buffer

Free each buffer

(K_IntFree)

Using

multiple buffers

or arrays?

Yes

Transfer data from each

buffer to a local array

(K_MoveBufToArray)

Read data

from each array

Convert data

from each array

Yes

Clear list of multiple

buffers or arrays

(K_BufListReset)

Free each frame

Operation complete

Additional Programming Flow Diagrams 3-11

Steps for a DMA-Mode Analog Input Operation

Access a frame for a virtual board

(K_GetADFrame)

Scanning

256 channels

or fewer?

Allocate a buffer

(K_DMAAlloc)

Specify the starting address

of the buffer

(K_SetDMABuf)

Continued on next page

Yes

Using

multiple

memory

buffers?

Yes

Allocate each buffer

(K_DMAAlloc)

Add each buffer to list

of multiple buffers

(K_BufListAdd)

3-12 Additional Features

Steps for a DMA-Mode Analog Input Operation (cont.)

Continued from previous page

Using a

channel-

gain

Using a

group of

consecutive

channels?

Yes

Specify the starting address

of the channel-gain queue

Deﬁne the

channel-gain

Visual

Basic?

(K_SetChnGAry)

Yes

queue

Using

Specify the ﬁrst and last channels

and the gain for all channels

K_SetStartStopChn and K_SetG)

Yes

(K_SetStartStopG or

Format the

channel-gain queue

(K_FormatChnGAry)

Modify the

channel-

gain

queue?

Yes

Restore the

channel-gain queue

(K_RestoreChnGAry)

Specify a single channel

(K_SetChn)

Specify the gain

for the single channel

(K_SetG)

Continued on next page

Additional Programming Flow Diagrams 3-13

Steps for a DMA-Mode Analog Input Operation (cont.)

Continued from previous page

Specify the clock source

(K_SetClk)

Using

internal

clock?

Specify the external clock edge

(K_SetExtClkEdge)

Scanning

256 channels

or fewer?

Yes

Set the clock rate

(K_SetClkRate)

Using paced

mode?

Specify burst conversion mode

(K_SetADFreeRun)

Set the burst mode conversion rate

(K_SetBurstTicks)

Yes

Specify paced conversion mode

(K_ClrADFreeRun)

Specify the buffering mode (K_SetContRun for continuous mode, K_ClrContRun for single-cycle mode)

Continued on next page

3-14 Additional Features

Steps for a DMA-Mode Analog Input Operation (cont.)

Continued from previous page

Using an

external

digital start

trigger?

Specify an internal start trigger

(K_SetTrig)

Scanning

256 channels

or fewer?

Yes

Specify an external start trigger

(K_SetTrig)

Specify digital

trigger conditions

(K_SetDITrig)

Using

post-trigger

acquisition?

Using

pre-trigger

acquisition?

Yes

(K_ClrAboutTrig)

Yes

(K_SetAboutTrig)

Disable the

about trigger

Enable the

about trigger

and specify

1 sample

Enable the

about trigger

and specify

the number of

post-trigger

samples

(K_SetAboutTrig)

Using an

internal start

trigger?

Continued on next page

Yes

Specify active

edge of the

about trigger

(K_SetDITrig)

Additional Programming Flow Diagrams 3-15

Steps for a DMA-Mode Analog Input Operation (cont.)

Continued from previous page

Using a

hardware

gate?

Disable the gate

(K_SetGate)

Setting up

another

virtual board?

Continued on next page

Yes

Specify the gate polarity

(K_SetGate)

Access a frame for the virtual board;

go to the top of page 3-12

3-16 Additional Features

Steps for a DMA-Mode Analog Input Operation (cont.)

Continued from previous page

Start the DMA-mode operation

(K_DMAStart)

Monitor the status of the operation

(K_DMAStatus)

Scanning

256 channels

or fewer?

Scanning

another

virtual

board?

Continued on next page

Yes

Using

continuous

buffering

mode?

Yes

Stop the operation

(K_DMAStop)

Additional Programming Flow Diagrams 3-17

Steps for a DMA-Mode Analog Input Operation (cont.)

Continued from previous page

Using

Visual

Basic?

Read data

from each buffer

Convert data

from each buffer

Free each buffer

(K_DMAFree)

Scanning

256 channels

or fewer?

Yes

Transfer data from each

buffer to a local array (K_MoveBufToArray)

Read data

from each array

Convert data

from each array

Yes

Using

multiple buffers

or arrays?

Yes

Clear list of multiple

buffers or arrays

(K_BufListReset)

Free each frame

Operation complete

3-18 Additional Features

Performing an Interrupt-Mode Operation

If DMA resources are not available, you can perform an analog input operation in interrupt mode. In interrupt mode, the SCAN-AD-HR board acquires a single sample or multiple samples from one or more logical channels (up to a maximum of 256) on the same virtual board. A hardware clock initiates conversions. Once the analog input operation begins, control returns to your application program. The hardware temporarily stores the acquired data in the FIFO on the SCAN-AD-HR board and then transfers the data to a user-deﬁned buffer in computer memory using an interrupt service routine.

Use the K_IntStart function to start the interrupt-mode operation on the ﬁrst virtual board, specifying the handle of the frame that deﬁnes the ﬁrst operation. After the SCAN-AD-HR board reads a sample from each logical channel associated with the virtual board and stores the samples in the user-deﬁned buffer, the operation stops. (Use the K_IntStatus function to monitor the status of the operation and determine when the operation stops.) Then, use K_IntStart again to start the interrupt-mode operation on the next virtual board, specifying the handle of the frame that deﬁnes the next operation.

Refer to page 3-6 for the procedure to follow when performing an interrupt-mode operation. In addition, example program 1, provided in the ASO-SCAN software package, illustrates how to acquire data in interrupt mode.

The data in the user-deﬁned buffer is stored as count values. Refer to Appendix A for information on converting the count value to voltage or degrees.

Performing an Interrupt-Mode Operation 3-19

Notes:

operation and start another, a slight delay occurs before the DAS-Scan system begins acquiring data on each subsequent virtual board.

Typically, you want your interrupt-mode operation to stop automatically after one sample from each logical channel has been read; this is referred to as single-cycle buffering mode. However, like DMA mode, if you are acquiring data from 256 logical channels or fewer, you can also perform the operation in continuous buffering mode. Continuous buffering mode allows you to continuously acquire data, overwriting any values already stored in memory. Refer to page 3-23 for more information.

In most cases, the information in Chapter 2 that applies to a DMA-mode operation also applies to an interrupt-mode operation. The following sections describe additional considerations and exceptions to keep in mind when performing an interrupt-mode operation.

Accessing a Frame

Like a DMA-mode operation, an interrupt-mode operation requires an A/D frame. Refer to page 2-7 for information about accessing a frame.

Because of the overhead required to stop one interrupt-mode

For interrupt mode, use the K_IntStart function (instead of the

K_DMAStart function) to start the operation you set up.

Reserving Memory

Like a DMA-mode operation, an interrupt-mode operation requires memory in which to store the acquired data. The recommended way to reserve memory for an interrupt-mode operation is to dynamically allocate a memory buffer for each virtual board. Refer to page 2-9 for more information.

For interrupt mode, use the K_IntAlloc function (instead of the

K_DMAAlloc function) to allocate the buffer. When you no longer

require the buffer, use the K_IntFree function (instead of the

K_DMAFree function) to free the buffer for another use.

3-20 Additional Features

Notes:

If you dynamically allocate a buffer of 256 samples (the typical size), an interrupt is generated after each sample and the samples are transferred one-by-one from the FIFO to the user-deﬁned buffer in computer memory. If your computer cannot service interrupts fast enough, a FIFO overﬂow error may occur. If you dynamically allocate a buffer of 512 samples (half of a FIFO), or any multiple of 512 samples, an interrupt is generated after 512 samples are acquired and the entire block of 512 samples is transferred from the FIFO to the user-deﬁned buffer in computer memory. To optimize an interrupt-mode operation, make sure that the size of your buffer is a multiple of 512 samples.

If you are writing Windows 95, 32-bit programs, you must install the Keithley Memory Manager. Refer to the DAS-Scan User’s Guide for information.

For interrupt mode, in addition to reserving memory by dynamically allocating a buffer, you can reserve memory by dimensioning an array within your application program’s memory area for each virtual board. A local array is directly accessible to your application program; for Visual Basic For Windows, you do not have to use the K_MoveBufToArray function to move the data from the dynamically allocated buffer to the program’s local array. However, unlike dynamically allocated buffers, which can be freed to make them available to other programs or processes, local arrays occupy permanent memory areas and cannot be freed. In addition, you cannot use local arrays with Windows 95, 32-bit programs.

Typically, a single array or buffer that can hold one sample for each logical channel associated with the virtual board is sufﬁcient. However, like DMA mode, if you are acquiring data from 256 logical channels or fewer, you can dimension a larger array/buffer or multiple arrays/buffers (up to a maximum of 150), allowing you to sample each logical channel multiple times. Use the K_IntAlloc function to dynamically allocate a memory buffer of up to 5,000,000 samples.

Performing an Interrupt-Mode Operation 3-21

If you are using large or multiple dynamically allocated memory buffers, you may be limited in the amount of memory you can allocate. It is recommended that you install the Keithley Memory Manager before you begin programming to ensure that you can allocate a large enough buffer or buffers. Refer to the DAS-Scan User’s Guide for more information about the Keithley Memory Manager.

Table 3-2 lists the functions used in interrupt mode to assign the starting addresses of local arrays or dynamically allocated buffers and to specify the number of samples to store in the buffers or arrays.

Table 3-2. Functions Used to Assign Starting Addresses

in Interrupt Mode

Language Type of Arrays or Buffers Function

C/C++ Single local array K_SetBuf

Multiple local arrays K_BufListAdd Single dynamically allocated buffer K_SetBuf Multiple dynamically allocated buffers K_BufListAdd

Visual Basic for Windows

Single local array K_SetBufI Multiple local arrays K_BufListAdd Single dynamically allocated buffer K_SetBuf Multiple dynamically allocated buffers K_BufListAdd

Specifying Channels and Gains

Like a DMA-mode operation, for an interrupt-mode operation, you can specify the logical channels on which to perform the operation and the gain at which to read the logical channels. Refer to page 2-11 for information about specifying the gain; refer to page 2-12 for information about specifying the logical channels.

3-22 Additional Features

Specifying a Pacer Clock

Like a DMA-mode operation, for an interrupt-mode operation, you can use a pacer clock to determine the period between the conversion of one logical channel and the conversion of the ne xt logical channel in a scan of multiple logical channels. Refer to page 2-19 for more information.

Typically, using the pacer clock alone is sufﬁcient. However, like DMA mode, if you are acquiring data from 256 logical channels or fewer, you can use both the pacer clock and the burst mode conversion clock to perform your operation in burst conversion mode. Refer to page 3-25 for more information about specifying burst conversion mode. Refer to page 3-26 for more information about using the burst mode conversion clock.

Specifying a Trigger

Like a DMA-mode operation, for an interrupt-mode operation, you can specify a start trigger for the ﬁrst virtual board to determine when acquisitions start. Refer to page 2-22 for more information.

Note that unlike DMA mode, in interrupt mode, you cannot use the about trigger to perform pre-trigger or about-trigger acquisitions.

Enabling a Hardware Gate

Like a DMA-mode operation, for an interrupt-mode operation, you can enable a hardware gate to determine when conv ersions can occur . Refer to page 2-24 for more information.

Specifying Continuous Mode

If you are reading 256 logical channels or fewer, you can specify continuous buffering mode. In continuous mode, the SCAN-AD-HR board continuously converts samples and stores them in memory until it receives a stop function. Any values already stored in memory are overwritten. Use the K_SetContRun function to specify continuous buffering mode.

Specifying Continuous Mode 3-23

If you specify the logical channels you want to read in either a group of consecutive logical channels or in a channel-gain queue, the speciﬁed channels are continuously sampled until the speciﬁed number of samples is read. For example, in a group of consecutive logical channels, the ﬁrst logical channel is 14, the last logical channel is 17, and you want to acquire ﬁve samples. Your program reads data ﬁrst from logical channel 14, then from logical channels 15, 16, and 17, and ﬁnally from logical channel 14 again.

Notes:

virtual board and later want to reset the buffering mode to single-cycle mode, use the K_ClrContRun function. In single-cycle mode, after the SCAN-AD-HR board converts one sample from each logical channel on the virtual board and stores the samples in memory, the operation stops automatically.

You cannot use continuous mode if you enable the generation of Windo ws ev ents. Refer to page 2-3 for more information about generating a Windo ws event.

If you specify continuous buffering mode for an operation on a

Reserving Large or Multiple Memory Buffers

Reserving a large memory buffer or multiple memory buffers is useful if you want to read each logical channel on a virtual board multiple times to average the data read from the channels.

If you are performing a DMA-mode analog input operation and you are reading 256 logical channels or fewer, you can use the K_DMAAlloc function to dynamically allocate a memory buffer of up to 65,536 samples. You can also dynamically allocate multiple memory buffers (up to a maximum of 150).

3-24 Additional Features

Use the K_SetDMABuf function to assign the starting address of a single dynamically allocated buffer.

Use the K_BufListAdd function to assign the starting addresses of multiple dynamically allocated buffers. Use the K_BufListReset function to clear the list of multiple buffers or arrays when you are through with them.

Specifying Burst Mode

If you are reading 256 logical channels or fewer, you can specify burst conversion mode. Burst mode is useful if you w ant a single external e v ent (such as the pulse of an external pacer clock) to start conv ersions of all the channels in a scan.

In burst mode, you use both the pacer clock and the burst mode conversion clock. The pacer clock determines the period between the conversions of one scan and the conversions of the next scan; the burst mode conversion clock determines the period between the conversion of one logical channel in a scan and the conversion of the next logical channel in the scan. Refer to page 2-19 for information about the pacer clock; refer to the next section for information about the burst mode conversion clock. Use the K_SetADFreeRun function to specify burst mode.

Notes:

board includes SCAN-BRD-V-ISO or SCAN-BRD-TC-ISO isolated assemblies.

If you specify burst conversion mode for an operation on a virtual board and later want to reset the conversion mode to paced mode, use the

K_ClrADFreeRun function. In paced mode, the pacer clock determines

the period between the conversion of one logical channel in a scan and the conversion of the next logical channel in the scan.

It is recommended that you do not use burst mode if a virtual

Specifying Burst Mode 3-25

Using the Burst Mode Conversion Clock

If you are reading 256 logical channels or fewer in burst conversion mode, you use the burst mode conversion clock to determine the period between the conversion of one logical channel in a scan and the conversion of the next logical channel in the scan.

Because the burst mode conversion clock uses a 1 MHz time base, each clock tick represents 1 the number of clock ticks between conversions. For example, if you specify 30 clock ticks, the period between conversions is 30 (33.33 ksamples/s).

You can specify from 10 clock ticks (100 kHz) to 64 clock ticks (15.625 kHz). The period between conversions ranges from 10 64

s. Use the K_SetBurstTicks function to specify

s to

When using the burst mode conversion clock, use the following formula to determine the number of clock ticks to specify:

clock ticks

For example, if you want a burst mode conversion rate of 10 ksamples/s, specify 100 clock ticks, as shown in the following equation:

1 000 000,,

-------------------------- -100=

1 MHz time base

---------------------------------------------------------------- -= burst mode conversion rate

10 000,

Specifying Pre-Trigger Acquisition

If you are performing a DMA-mode analog input operation and you are reading 256 logical channels or fewer , you can use pre-trigger acquisition to acquire data before a speciﬁc trigger event.

3-26 Additional Features

You specify both a start trigger and an about trigger. The start trigger determines when acquisitions start on a virtual board and can be either an internal trigger or an external digital trigger. The about trigger is always an external digital trigger; acquisitions stop on the virtual board when the about-trigger event occurs. Refer to page 2-23 for information about an internal trigger; refer to page 2-23 for information about an external digital trigger.

To specify pre-trigger acquisition, perform the following steps:

1. Specify the start trigger.

– Use K_SetTrig to specify an internal or an external trigger

source.

– If you specify an external start trigger in K_SetTrig , use

K_SetDITrig to specify the active edge for the digital trigger.

2. Use K_SetAboutTrig to enable the about trigger and to set the

number of samples to 1.

Note:

The minimum number of samples that you can specify in

K_SetAboutTrig is 1.

3. Specify the active edge for the about trigger, if necessary.

– If the start trigger is an internal trigger, use K_SetDITrig to

specify the active edge for the about trigger.

– If the start trigger is an external digital trigger, the active edge

used for the start trigger is also used for the about trigger. It is not

necessary to use K_SetDITrig again.

Notes:

If you specify pre-trigger acquisition for an operation on a virtual board and later want to reset the operation for post-trigger acquisition, use the K_ClrAboutTrig function to disable the about trigger.

Pre-trigger acquisition is not available with interrupt-mode operations.

Specifying Pre-Trigger Acquisition 3-27

Specifying About-Trigger Acquisition

If you are performing a DMA-mode analog input operation and you are reading 256 logical channels or fewer, you can use about-trigger acquisition to acquire data both before and after a speciﬁc trigger event.

You specify both a start trigger and an about trigger. The start trigger determines when acquisitions start on a virtual board and can be either an internal trigger or an external digital trigger. The about trigger is always an external digital trigger; acquisitions stop after a speciﬁed number of samples has been acquired on the virtual board after the about-trigger event occurs. Refer to page 2-23 for information about an internal trigger; refer to page 2-23 for information about an external digital trigger.

To specify about-trigger acquisition, perform the following steps:

1. Specify the start trigger.

– Use K_SetTrig to specify an internal or an external trigger

source.

– If you specify an external start trigger in K_SetTrig , use

K_SetDITrig to specify the active edge for the digital trigger.

2. Use K_SetAboutTrig to enable the about trigger and to specify the

desired number of post-trigger samples.

3. Specify the active edge for the about trigger, if necessary.

– If the start trigger is an internal trigger, use K_SetDITrig to

specify the active edge for the about trigger.

– If the start trigger is an external digital trigger, the active edge

used for the start trigger is also used for the about trigger. It is not

necessary to use K_SetDITrig again.

Notes:

virtual board and later want to reset the operation for post-trigger acquisition, use the K_ClrAboutTrig function to disable the about trigger.

About-trigger acquisition is not available with interrupt-mode operations.

3-28 Additional Features

If you specify about-trigger acquisition for an operation on a

Data Formats

This appendix contains the following sections:

Converting Counts to Voltage - instructions for converting a count

●

value returned by the DAS-Scan Function Call Driver to a voltage value.

Converting Counts to Temperature - instructions for converting a

●

count value returned by the DAS-Scan Function Call Driver to a temperature value.

Converting Counts to Voltage

The DAS-Scan Function Call Driver can read count values only. When reading an analog input value (as in K_ADRead ), you can convert the count value returned by the DAS-Scan Function Call Driver to a voltage value. If you are using a SCAN-BRD-TC or SCAN-BRD-TC-ISO assembly and want to express the value in degrees, you can then convert the voltage value to a temperature value; refer to the next section for information.

To convert an analog input value to a voltage, use the follo wing equation, where count is the count value and span is the span in volts (refer to T able A-1):

Voltage

count span×

-------------------------------- -= 65536

Converting Counts to Voltage A-1

−

Table A-1. Span Values For Data Conversion Equations

Input Range Type Gain

Unipolar 1 0 to 10 V 10

2 0 to 5 V 5 4 0 to 2.5 V 2.5 8 0 to 1.25 V 1.25 50 0 to 0.2 V 0.2 100 0 to 0.1 V 0.1 200 0 to 50 mV 0.05 400 0 to 25 mV 0.025

Bipolar 1

2 4 8 50 100

Analog Input Range

10 to 10 V 20 5 to 5 V 10

2.5 to 2.5 V 5

1.25 to 1.25 V 2.5

0.2 V to 0.2 V 0.4

0.1 V to 0.1 V 0.2

Span (V)

200 400

50 mV to 50 mV 0.1 25 mV to 25 mV 0.05

For example, assume that you want to read analog input data from a channel conﬁgured for a bipolar input range type; the channel collects the data at a gain of 2. The count value is 1024. The voltage is determined as follows:

1024 10× V

------------------------------ 0.156 V= 65536

A-2 Data Formats

Converting Counts to Temperature

If you are using a SCAN-BRD-TC or SCAN-BRD-TC-ISO assembly, you can convert the count value returned by the DAS-Scan Function Call Driver to a temperature value. Refer to example program 4, provided in the ASO-SCAN software package, as you perform the procedure described in this section.

To convert a count value to a temperature value, perform the following steps:

1. Convert the thermocouple count value returned by the DAS-Scan Function Call Driver to thermocouple voltage. Refer to page A-1 for information.

2. If you are using the CJC channels, convert the CJC count value returned by the DAS-Scan Function Call Dri ver to CJC v oltage, using a gain of 1. Refer to page A-1 for information.

3. Convert the CJC voltage to and then convert the

Note:

Because the CJC sensors used on the DAS-Scan system

generate 10 mV per

K to

K, you must divide the CJC voltage by 0.010.

K by dividing the CJC voltage by 0.010,

Converting Counts to Temperature A-3

4. Adjust the thermocouple voltage to take into account the CJC temperature value, using the appropriate intercept and slope values.

Notes:

The thermocouple voltage is a relative value, based on the difference between the voltage at the end of the wire and the voltage at the screw terminal panel; the CJC temperature is an absolute value. You must ﬁrst convert the CJC temperature to mV, based on the thermocouple type you are using, and then add the two voltage values together.

The intercept and slope values used in the example program assume that the temperature of the CJC sensor is approximately 25

C. If the temperature of your CJC sensor is different, use the appropriate N.I.S.T thermocouple table to determine the appropriate intercept value, and substitute an appropriate slope value.

5. Calculate the index into the thermocouple lookup table, using the voltage step interval (mV) and starting voltage (mV) from the [header] section of the appropriate table. Lookup tables for J, K, T, E, R, S, and B type thermocouples are provided in the ASO-SCAN software package.

6. Interpolate between the two nearest entries in the lookup table to determine the true reading in

A-4 Data Formats

Index

A/D frame elements about-trigger acquisition accessing a frame address of memory buffer address of SCAN-BRD assembly allocating memory analog input operations analog input range

3-21

array ASO-SCAN software package

bipolar range type board initialization

2-9

buffer buffer address buffer address functions buffering mode buffering mode functions burst mode burst mode conversion clock

3-25

2-10

2-6

2-9

2-7

2-9

2-11

2-2

3-22

3-24

3-20

2-5

3-28

2-10

3-20

1-5

3-2

3-25

1-2

3-22

2-12

3-26

channel functions channel-gain queue CJC channel clock functions clock: see burst mode conversion clock,

pacer clock commands: see functions continuous mode conversion mode conversion mode functions conversion rate converting

counts to temperature counts to voltage

2-18

1-5

2-21

1-5

2-18

2-19

3-3

3-23 2-20

3-26

A-1

A-3

3-25

A-3

3-2

DAS-Scan Function Call Driver: see

Function Call Driver DASSCAN_EventDisable DASSCAN_EventEnable data transfer modes: see operation modes device handle digital trigger DMA mode driver handle driver: see Function Call Driver

2-2

2-23

1-9

2-1

2-5

3-12

2-3

channel

channel-gain queue CJC group of consecutive logical channels

2-12

2-18

3-22

2-19

2-17

2-18

elements of frame error handling

2-3

event external digital trigger external pacer clock

2-9

2-4

2-21

2-23

X-1

flow diagrams frame

frame management functions Function Call Driver

functions

2-7

3-20

elements handle

initialization

2-7

1-4

buffer address buffering mode channel

1-5

clock conversion mode DASSCAN_EventDisable DASSCAN_EventEnable frame management

1-5

gain

1-6

gate initialization memory management miscellaneous 1-6 operation 1-4, 3-2 trigger 1-6, 3-3

2-9

1-5

1-6

3-2

3-3

2-1

1-4

3-3

1-5

3-2

1-4

1-5

1-4

2-3

3-2

handle

device driver 2-1 frame 2-7

memory 2-10 handling errors 2-4 hardware gate 3-23 hardware gate: see gate help

2-2

1-14

initialization functions 1-4 initializing

board

2-2

driver 2-1 input range type 2-11 installation tasks 1-2 internal pacer clock 2-20 internal trigger 2-23 interrupt mode 3-6, 3-19 interrupts 2-3, 3-21

gain code 2-11 gain functions 1-5 gain: see analog input range gate

2-24, 3-23

gate functions 1-6 generating a Windows event 2-3 group of consecutive logical channels 2-17

X-2 Index

K_ADRead 2-5, 2-17 K_BufListAdd 3-25 K_BufListReset 3-25 K_ClearFrame 2-8 K_CloseDriver 2-2 K_DASDevInit 2-3 K_DMAAlloc 2-9, 3-24 K_DMAFree 2-10 K_DMAStart 2-6 K_DMAStatus 2-6 K_FreeDevHandle 2-3 K_FreeFrame 2-8

K_GetADFrame 2-7 K_GetDevHandle 2-2 K_GetErrMsg 2-4 K_GetShellVer 2-4 K_GetVer 2-4 K_IntAlloc 3-20 K_IntFree 3-20 K_IntStart 3-19 K_IntStatus 3-19 K_MoveBufToArray 2-10 K_OpenDriver 2-1 K_SetADFreeRun 3-25 K_SetADMode 2-11 K_SetBurstTicks 3-26 K_SetChn 2-17 K_SetChnGAry 2-18 K_SetClk 2-21 K_SetClkRate 2-20 K_SetContRun 3-23, 3-24 K_SetDITrig 2-23 K_SetDMABuf 2-10, 3-25 K_SetExtClkEdge 2-21 K_SetG 2-17 K_SetGate 2-24 K_SetStartStopChn 2-17 K_SetStartStopG 2-17 K_SetTrig 2-23 Keithley Memory Manager 3-22

maintenance operations: see system

operations managing memory: see allocating memory memory memory address 2-10, 3-22 memory allocation: see allocating memory memory handle memory management functions 1-5, 3-2 message 2-3 miscellaneous functions 1-6 miscellaneous operations: see system

multiple arrays multiple buffers 3-21, 3-24

2-9

2-10

operations

3-21

operation

analog input DMA-mode 1-9, 2-5, 3-12 interrupt-mode 3-6, 3-19 single-mode 1-8, 2-5, 3-5

system 2-1 operation functions 1-4, 3-2 operation modes 2-5

2-5

large array 3-21 large buffer 3-21, 3-24 local array 3-21 logical channel 2-2, 2-12

paced mode 2-20, 3-25 pacer clock 2-19, 3-23, 3-25 physical channel 2-2, 2-12 post-trigger acquisition 2-22 pre-trigger acquisition 3-26 procedures 1-6, 3-3 programming flow diagrams 1-6, 3-3

X-3

reinitializing a board 2-3 return values 2-4 revision levels 2-4 routines: see functions

scan 2-12, 2-17, 3-26 SCAN-AD-HR board 2-2, 2-12 SCAN-BRD assembly 2-2, 2-12 setup tasks 1-2 single mode 1-8, 2-5, 3-5 single-cycle mode 2-6, 3-20, 3-24 software trigger: see internal trigger start trigger starting analog input operations 2-5 status codes 2-4 summary of functions 1-4, 3-2 system operations 2-1

2-22

virtual board 2-2, 2-12

Windows event 2-3

tasks

installation setup 1-2

technical support 1-14 time base

burst mode conversion clock

internal pacer clock 2-20 trigger 2-22, 3-23 trigger functions 1-6, 3-3 troubleshooting 1-14

1-2

3-26

unipolar range type 2-11

X-4 Index

Tektronix DAS-Scan Function Call Driver Users Guide

Specifications and Main Features

Frequently Asked Questions

User Manual