LinearX LT360 Programming Manual

Precision Turntable

DLL Programming Manual

DLL Programming Manual

LT360 Precision Turntable

1

DLL Programming Manual

LT360 Precision Turntable
DLL Programming Manual

LT360LIB.DLL Win32 OS

© 2006 LINEARX SYSTEMS INC.
All Rights Reserved.

Tel: [phone]
Fax: [phone]

Printed in the United States of America.
March 30, 2006.

This document was produced on a Pentium-4 / 2GHz PC with Win2K using Adobe PageMaker 7.0, Adobe
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captures. Final masters were produced using an Xerox Docutech image setter. Help files were composed and
compiled using Windows Help Designer 3.1.

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LT360 Precision Turntable

DLL Programming Manual

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LT360 Precision Turntable

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DLL Programming Manual

Technical Support

LinearX provides detailed printed manuals and on-line help within the program as the primary
source for user information and assistance regarding the use of this product. If these sources do
not contain the answers to your questions, contact LinearX via any of the following methods:

Internet Forums: www.linearx.com/forums
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When contacting us regarding a technical support issue, PLEASE follow these steps to aid us in
understanding and solving your problem:

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Technical support hours are: Monday-Friday 9:00AM to 5:00PM Pacific Standard Time.

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LT360 Precision Turntable

DLL Programming Manual

Contents

Chapter 1: Overview 7

1.1 Overview of LT360LIB.DLL ........................................................ 7

1.2 Header / Include Files ............................................................ 8

1.3 Opening and Closing a Link ..................................................... 9

1.4 Error Messages ...................................................................... 11

1.5 Using LT360 Commands ..................................................... 16

Chapter 2: Command Reference 17

2.1 Goto CCW .......................................................................... 17

2.2 Goto CW ........................................................................... 18

2.3 Step CCW ..................................................................... 19

2.4 Step CW .................................................................... 20

2.5 Set Smart Torque .................................................... 21

2.6 Set Baud Rate ......................................................... 22

2.7 Set Origin .................................................................... 23

2.8 Set Pulse Direction ........................................................ 24

2.9 Set Pulse Edge ........................................................... 25

2.10 Set Step Size .......................................................... 26

2.11 Set Velocity ........................................................... 27

2.12 Set Torque ............................................................ 28

2.13 Set Acceleration Function .......................................... 29

2.14 Set Name ............................................................... 31

2.15 Set Pulse Input ...................................................... 32

2.16 Set Analog Input ...................................................... 33

2.17 Set Display Polarity ................................................ 34

2.18 Set Input Polarity ................................................... 35

2.19 Set Output Polarity ................................................ 36

2.20 Set Move Abort .................................................... 37

2.21 Set Motor Home Check ......................................... 38

2.22 Set Output Mode .................................................... 39

2.23 Get Name ............................................................... 41

2.24 Get Title ................................................................. 42

2.25 Get Firmware Version ............................................. 43

2.26 Get Firmware Date .................................................. 44

2.27 Get Production Date .................................................. 45

2.28 Get Calibration Date .................................................. 46

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Contents

2.29 Get Calibration Due ..................................................... 47

2.30 Get Serial Number ...................................................... 48

2.31 Get Baud Rate ............................................................ 49

2.32 Get Position ............................................................ 50

2.33 Get Pulse Direction ................................................... 51

2.34 Get Pulse Edge .......................................................... 52

2.35 Get Step Size ........................................................... 53

2.36 Get Velocity ............................................................ 54

2.37 Get Torque ............................................................ 55

2.38 Get Acceleration Function ........................................ 56

2.39 Get Moving ............................................................ 58

2.40 Get Pulse Input ......................................................... 59

2.41 Get Analog Input .................................................... 60

2.42 Get Smart Torque ....................................................... 61

2.43 Get Display Polarity .................................................... 62

2.44 Get Input Polarity ...................................................... 63

2.45 Get Output Polarity ................................................... 64

2.46 Get Motor Home Check .............................................. 65

2.47 Get Revision Code ....................................................... 66

2.48 Get Output Mode ........................................................... 67

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1.1 Overview of LT360LIB.DLL

A DLL (Dynamic Link Library) is provided for use by user application
programs to allow direct control of the LT360 Precision Turntable. The DLL
supports the Win32 OS environments. For other operating system environ­ments, the universal RS-232 programming method should be used.

The DLL supports both methods of linking to LT360 turntables either via
serial RS-232 connections or the USB (Universal Serial Bus). Multiple LT360
units can be managed by the DLL simultaneously, from 1 to 128 units.

The DLL handles all of the management details necessary for easy serial
communications over either the PC's com ports or USB. The application
program needs only to place calls to the DLL through 4 simple functions.

The LT360LIB.DLL file should be placed in a folder where the Windows
system can find it. Typically placing a copy in the application folder is
common, or in the main Windows folder.

LT360 Precision Turntable

The DLL functions are 32 bit code and can be called by any Win32 applica­tion written in any language. An appropriate header file is all that is required
for the exported functions for linking.

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1.2 Header / Include Files

Two example header / include files for linking and calling the DLL
functions are provided for C/C++ or Delphi/Pascal:

Header / Include Files

■ LT360LIB.h C/C++

■ LT360LIB.pas Delphi/Pascal

Other header files for different languages can be translated from these
examples. The header files contain all of the prototype exported
functions along with the command identifier constants used to make the
various function calls to the LT360 turntables.

The header files may require modification depending on the particular
behavior of the compiler/linker being used.

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DLL Programming Manual

1.3 Opening and Closing a Link

The procedure for opening a link is very easy. First connect an LT360 to
either a serial COM port or USB port on the computer. Then call one of
two functions to open the link:

LONGINT LT360LIB_OpenLinkUSB(void);

LONGINT LT360LIB_OpenLinkCOM(LONGINT ComNum, LONGINT BaudRate);

■ LT360LIB_OpenLinkUSB
This call is used if the turntable is connected to the USB bus. There are no
parameters. Since there may be multiple LT360 units attached to the USB
bus, this function can be called more than once.

The function returns a Handle to each unit found, which is simply a numeric
index. The calling program should maintain and store these handles. If no
more LT360 units are found, then the handle returned is 0.

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Note: The USB driver for the LT360 must be installed in the Win32 system.

■ LT360LIB_OpenLinkCOM
This call is used if the turntable is connected to a serial COM port. There
are two parameters: the COM port number (ie. 1,2,3,4...) and the baud rate.
The default baud rate shipped with the LT360 is 9600. You must specify
the COM port number in which the LT360 is connected. The function may
be called multiple times with different com port numbers for LT360 units
attached to the different com ports.

The function returns a Handle to the unit found, which is simply a numeric
index. The calling program should maintain and store these handles. If no
LT360 unit is found, then the handle is 0.

Note: The 9 pin serial cable should be straight-through, not null modem.

■ LT360LIB_CloseLink
To close a link to an LT360, call this function with the handle of the unit.
The return value is True if successful, and false if an error.

LONGBOOL LT360LIB_CloseLink(LONGINT Handle);

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DLL Programming Manual

■ Example with USB link
The following code fragment demonstrates the sequence of calls for a
USB link to a LT360 unit.

// Open link via USB, save returned handle

H360 = LT360LIB_OpenLinkUSB();

...
// Call the LT360 to set the Step Size to 1 degree

LT360LIB_CmdValue(H360,lt_SetStepSize,'1.0');

// Call the LT360 to do a step CCW

LT360LIB_CmdValue(H360,lt_Step_CCW,null);

...
// Close the link when done

LT360LIB_CloseLink(H360);

10

■ Example with COM link
The following code fragment demonstrates the sequence of calls for a
RS-232 serial port link to a LT360 unit.

// Open link via serial port, COM3 at 9600 baud, save returned handle

H360 = LT360LIB_OpenLinkCOM(3,9600);

...
// Call the LT360 to set the Step Size to 1 degree

LT360LIB_CmdValue(H360,lt_SetStepSize,'1.0');

// Call the LT360 to do a step CCW

LT360LIB_CmdValue(H360,lt_Step_CCW,null);

...
// Close the link when done

LT360LIB_CloseLink(H360);

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DLL Programming Manual

1.4 Error Messages

The LT360 can display a variety of error codes on the front panel
display. The error message will be displayed over a 4 second interval
with a format such as Err0 or Er13.

The following list describes some of the error codes which can appear:

//------------------------------------------------­// Show Error Display Codes
//------------------------------------------------­// 0 - Motor Home Position Error
// 1 - RS232-OE Overrun Error
// 2 - RS232-PE Parity Error
// 3 - RS232-FE Framing Error
// 4 - RS232-BI Break Int Error
// 5 - RS232 Unknown Command
// 6 - RS232 Invalid Parameter
// 7 - RS232 Invalid Return
// 8 - USB Unknown Command
// 9 - RS232 Command Timeout
// 10 ­// 11 - Display Cntrlr Adr Failure
// 12 - Switch Cntrlr Adr Failure
// 13 - Torque Cntrlr Adr Failure
// 14 - Output Cntrlr Adr Failure
// 15 ­// 16 ­// 17 ­// 18 ­// 19 ­// 20 ­//-------------------------------------------------

Most errors produced by the LT360 will be RS-232 command or
parameter errors, especially if the user is programming via RS-232. The
USB processing routines also rely on the RS-232 command decoders, so
it is very possible to see RS-232 error codes while using the USB
interface.

The basic LT360 serial RS-232 communication parameters are: 9600
baud, 8 data bits, no parity, 1 stop bit, and no flow control.

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Error - 0 : Motor Home Position Error

The stepper motor produces a specific number steps for a given amount
of platter rotation. The LT360 utilizes microstepping for additional
precision control. One particular phase of the motor is designated as
the Home position. For any given platter rotation, the motor should
always end in its Home position. This can be checked by the firmware
continuously, if the MotorHomeChk option is enabled. If the motor
position is not in the Home phase at the end of a movement, this error
will be shown.

In normal operation this error should never occur. If it does, the unit
must be powered off, or the MotorHomeChk option disabled, to clear
the error. It is possible for this error to be produced by noise in the
stepper motor controller, or by the load exceeding the torque capability
thereby causing the motor to skip steps.

If this error is shown repeatedly, either there is a problem internal in the
LT360 or the torque load is too great for the drive system.

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Error - 1 : RS232-OE Overrun Error

This error indicates problems with the serial port communications. It
can be caused by differences in the communication parameters be­tween the computer and the LT360. Make sure that the computer serial
port setup is 9600 baud, 8 data bits, no parity, and 1 stop bit. If the
LT360 baud rate has been changed, then the PC must be set the same.

Error - 2 : RS232-PE Parity Error

This error indicates problems with the serial port communications. It
can be caused by differences in the communication parameters be­tween the computer and the LT360. Since the LT360 does not use
parity, this error is unlikely. Make sure that the computer serial port
setup is 9600 baud, 8 data bits, no parity, and 1 stop bit. If the LT360
baud rate has been changed, then the PC must be set the same.

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DLL Programming Manual

Error - 3 : RS232-FE Framing Error

This error indicates problems with the serial port communications. It can be
caused by differences in the communication parameters between the
computer and the LT360, or invalid parameters in the computer UART of
the computer. Make sure that the computer serial port setup is 9600 baud,
8 data bits, no parity, and 1 stop bit. If the LT360 baud rate has been
changed, then the PC must be set the same. You may also need to reboot
the computer to clear and reinitialize the UART in the computer.

Error - 4 : RS232-BI Break Int Error

This error indicates problems with the serial port communications. It can be
caused by differences in the communication parameters between the
computer and the LT360. Make sure that the computer serial port setup is
9600 baud, 8 data bits, no parity, and 1 stop bit. If the LT360 baud rate has
been changed, then the PC must be set the same.

LT360 Precision Turntable

Error - 5 : RS232 Unknown Command

This error indicates that the character string sent to the LT360 did not
contain a valid command. This error will generally occur if you are writing
your own RS-232 program, and there are bugs in your program. Check the
command strings being sent to verify that they contain valid LT360 com­mands. Case is not important, but spaces in the right or wrong places can
make a difference.

Error - 6 : RS232 Invalid Parameter

This error indicates that the LT360 was expecting a parameter value for this
command, but did not find one in the command string. Some commands
need parameters and some do not. This error will generally occur if you are
writing your own RS-232 program, and there are bugs in your program.
Check the command strings being sent to verify that they contain valid
LT360 commands and parameters. Case is not important, but spaces in the
right or wrong places can make a difference.

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DLL Programming Manual

Error - 7 : RS232 Invalid Return

This error indicates that the LT360 was expecting to produce a return
value for a Get command, but the return value was an empty string.
This error will generally occur if you are writing your own RS-232
program, and there are bugs in your program. Check the command
strings being sent to verify that they contain valid LT360 commands
and/or parameters. Case is not important, but spaces in the right or
wrong places can make a difference.

Error - 8 : USB Unknown Command

This error indicates that the LT360 did not understand the command
index sent via USB. This error is very uncommon. It probably indicates
faulty communication over USB, such as a cable being disconnected or
dirty connections. Possibly some other unusual problem.

Error - 9 : RS232 Command Timeout

This error indicates that the LT360 received some characters, but never
received a termination character [Null(0) or CR(13)] before the 10
second timeout expired. When the first character is sent to the LT360, a
timer is started. If a termination character is not received within 10
seconds, then this error is produced and the command buffer is cleared.
Receiving all of the characters for a command string should take very
little time, on the order of micro or milli seconds, so if a termination
charcater does not arrive within 10 seconds, something is wrong. The
LT360 uses this timeout to clear the command buffer every 10 seconds
if characters are received with no termination character. The termina­tion character is mandatory to notify the LT360 that the entire com­mand string has been sent and it can now process it.

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Error - 11: Display Controller Address Failure

This error indicates that the CPU in the LT360 cannot communicate with the
display controller. This error should never occur. If it does, a failure of a
component in the LT360 is indicated.

Error - 12: Switch Controller Address Failure

This error indicates that the CPU in the LT360 cannot communicate with the
switch controller. This error should never occur. If it does, a failure of a
component in the LT360 is indicated.

Error - 13: Torque Controller Address Failure

This error indicates that the CPU in the LT360 cannot communicate with the
stepper motor torque DAC controller. This error should never occur. If it
does, a failure of a component in the LT360 is indicated.

LT360 Precision Turntable

Error - 14: Output Controller Address Failure

This error indicates that the CPU in the LT360 cannot communicate with the
analog output DAC controller. This error should never occur. If it does, a
failure of a component in the LT360 is indicated.

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DLL Programming Manual

LONGBOOL LT360LIB_CmdValue(LONGINT Handle, LONGINT CmdID, char *ParamValue);

1.5 Using LT360 Commands

The commands which a typical user application needs can all be called
using a single function:

This function has three parameters and returns a true/false result for
success or failure. The first parameter is the Handle to the LT360 unit
(returned from the OpenLink calls), the second parameter is the
Command Identifier, and the third parameter is a ParamValue string
(ASCIIZ string).

All user commands for the LT360 are sent using this function with
various command identifiers. They are described in the header files,
and on the following pages. The ParamValue string pointer is used both
as an In/Out parameter to send data or receive data from the LT360.

16

For some Set commands that do not require a parameter, this value can
be null/nil. For Get commands which return a value, the user must
supply a string pointer to the user allocated character space. Generally
32 characters of space is adequate for all command value returns.

Commands fall into two categories: Set and Get. Set commands are
Out commands which can send data to the LT360. Get commands are
In commands which return data from the LT360. Some Set commands
may or may not have a parameter value.

Numeric values sent as parameters to the LT360 must be converted into
a string. They are also returned as a string.

If the command or data sent to an LT360 is incorrect, an error message
will be displayed on the LT360 front panel. The function above will only
reflect an error if there is a problem with the data transmission.

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DLL Programming Manual

2.1 Goto CCW

■ Class Set (out)

■ Identifier lt_Goto_CCW

■ Hex Value 0x1C

■ Call LT360LIB_CmdValue(Handle, lt_Goto_CCW, '±nnn.n');

■ Parameter Position (degrees)

Description

This command causes the LT360 to move to the desired location specified
by the parameter value using counter clockwise rotation. If the LT360 is
already at this location, no movement occurs.

The parameter value should have tenths of a degree precision, and may be
either unipolar (0..+360.0) or bipolar (0..±180.0).

The Goto 0 command can also be issued from the front panel of the unit, or
the LR360 remote using the switches on the front panel.

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2.2 Goto CW

■ Class Set (out)

■ Identifier lt_Goto_CW

■ Hex Value 0x1D

■ Call LT360LIB_CmdValue(Handle, lt_Goto_CW, '±nnn.n');

■ Parameter Position (degrees)

Description

This command causes the LT360 to move to the desired location
specified by the parameter value using clockwise rotation. If the LT360
is already at this location, no movement occurs.

The parameter value should have tenths of a degree precision, and may
be either unipolar (0..+360.0) or bipolar (0..±180.0).

The Goto 0 command can also be issued from the front panel of the
unit, or the LR360 remote using the switches on the front panel.

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2.3 Step CCW

■ Class Set (out)

■ Identifier lt_Step_CCW

■ Hex Value 0x1E

■ Call LT360LIB_CmdValue(Handle, lt_Step_CCW, null);

■ Parameter (none)

Description

This command causes the LT360 to move from its current position by the
current step size using counter clockwise rotation. No parameter is re­quired.

The step command can also be issued from the front panel of the unit, the
LR360 remote, or by the TTL Pulse input on the front panel.

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2.4 Step CW

■ Class Set (out)

■ Identifier lt_Step_CW

■ Hex Value 0x1F

■ Call LT360LIB_CmdValue(Handle, lt_Step_CW, null);

■ Parameter (none)

Description

This command causes the LT360 to move from its current position by
the current step size using clockwise rotation. No parameter is re­quired.

The step command can also be issued from the front panel of the unit,
the LR360 remote, or by the TTL Pulse input on the front panel.

The parameter value should have tenths of a degree precision, and may
be either unipolar (0..360.0) or bipolar (0..±180.0).

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2.5 Set Smart Torque

■ Class Set (out)

■ Identifier lt_SetSmartTorque

■ Hex Value 0x20

■ Call LT360LIB_CmdValue(Handle, lt_SetSmartTorque, 'xxx');

■ Parameter 'OFF' or 'ON'

Description

This command controls the behavior of the stepper motor. When
SmartTorque is set ON, the motor is powered down to half the driving
power 2 seconds after each movement stops. Motor power is returned to
full (as controlled by the Maximum Torque setting) when the motor starts
again.

This feature takes advantage of the fact that the worm gear drive system
employed by the LT360 is irreversible. Meaning, the platter is self-locking at
its current position. The load cannot rotate the platter itself. Therefore, it is
not necessary to maintain full power on the motor merely to hold its current
position when the platter is not in movement.

LT360 Precision Turntable

The use of SmartTorque greatly reduces the thermal heating in the motor
and driver circuitry, and produces a very efficient drive system. Under most
conditions and use, this feature should always be kept ON.

If a particular application demands that the motor power be kept constant at
all times, even when stationary (SmartTorque=OFF), then the maximum
torque should be to 70% or less to prevent excessive heating. It is difficult
to envision what kinds of applications would require this behavior, but the
option is available if needed.

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2.6 Set Baud Rate

■ Class Set (out)

■ Identifier lt_SetBaudRate

■ Hex Value 0x21

■ Call LT360LIB_CmdValue(Handle, lt_SetBaudRate, 'nnnnn');

■ Parameter Baud rate, eg. '9600'

Description

This command sets the baud rate for RS-232 communications. Once
the new baud rate is set, all further RS-232 communication with an
LT360 must be at the new baud rate.

Legal baud rate values are:

9600
14400
19200
38400
57600

22

Note: Increasing the baud rate will not necessarily produce a direct effect
on the speed of communication and commands with the LT360. The
LT360 has a response time for commands which is dependent on many
factors internally. The CPU must perform many other tasks so there can
be a 1-25 mSec latency before the commands are processed regardless of
the baud rate.

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2.7 Set Origin

■ Class Set (out)

■ Identifier lt_SetOrigin

■ Hex Value 0x22

■ Call LT360LIB_CmdValue(Handle, lt_SetOrigin, null);

■ Parameter (none)

Description

This command resets the rotational origin to that of the current platter
position. No parameters are required, and the platter does not rotate. All
further goto commands will be referenced to this new origin (0.0).

LT360 Precision Turntable

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DLL Programming Manual

2.8 Set Pulse Direction

■ Class Set (out)

■ Identifier lt_SetPulseDir

■ Hex Value 0x23

■ Call LT360LIB_CmdValue(Handle, lt_SetPulseDir, 'xxx');

■ Parameter 'CCW' or 'CW'

Description

This command controls the behavior to a TTL step pulse at the Pulse
input BNC connector. The parameter string can be either CCW or CW,
meaning counter clockwise or clockwise.

When a pulse arrives at the Pulse BNC input, the platter will rotate
either CCW or CW as defined by this setting. The size of the step is
controlled by the Set StepSize command.

Note: The TTL pulse should be a minimum of 10uS, or longer. The
triggering edge can be controlled by the Set PulseEdge command.

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2.9 Set Pulse Edge

■ Class Set (out)

■ Identifier lt_SetPulseEdge

■ Hex Value 0x24

■ Call LT360LIB_CmdValue(Handle, lt_SetPulseEdge, 'xxxx');

■ Parameter 'RISE' or 'FALL'

Description

This command controls the behavior to a TTL step pulse at the Pulse input
BNC connector. The parameter string can be either RISE or FALL, meaning
triggering occurs on the rising or falling edge of the pulse.

When a pulse arrives at the Pulse BNC input, the platter will rotate either at
the rising or falling edge as defined by this setting. The size of the step is
controlled by the Set StepSize command.

Note: The TTL pulse should be a minimum of 10uS, or longer. The direction
can be controlled by the Set PulseDir command.

LT360 Precision Turntable

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DLL Programming Manual

2.10 Set Step Size

■ Class Set (out)

■ Identifier lt_SetStepSize

■ Hex Value 0x25

■ Call LT360LIB_CmdValue(Handle, lt_SetStepSize, 'nn.n');

■ Parameter Step Size (degrees)

Description

This command sets the angular step size by which the platter will rotate
to either a step command or TTL pulse. The parameter string must
contain a numeric value such as '15.0' with tenth of a degree precision.

The minimum step size is 0.1 degrees. Step size is always positive.
Direction is controlled by the CCW/CW commands listed else where.

26

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DLL Programming Manual

2.11 Set Velocity

■ Class Set (out)

■ Identifier lt_SetVelocity

■ Hex Value 0x26

■ Call LT360LIB_CmdValue(Handle, lt_SetVelocity, 'n.nn');

■ Parameter Velocity (RPM)

Description

This command sets the angular velocity by which the platter will rotate. The
value is set in RPM (revolutions per minute). The allowable range for the
parameter is 0.01 to 3.00 RPM.

The parameter string must contain a numeric value such as '1.00' with
hundreths precision.

LT360 Precision Turntable

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DLL Programming Manual

2.12 Set Torque

■ Class Set (out)

■ Identifier lt_SetTorque

■ Hex Value 0x27

■ Call LT360LIB_CmdValue(Handle, lt_SetTorque, 'nnn.n');

■ Parameter Torque (%)

Description

This command sets the stepper motor torque for the platter rotation.
The value is set in percent of maximum torque. The allowable range for
the parameter is 10.0 to 100.0 %.

The parameter string must contain a numeric value such as '100.0' with
tenths of a degree precision.

For most typical applications your will want the torque set to 100%. If
you intend to have the platter in constant motion, than you may wish to
set the torque to a lower value such as 70%. This will reduce heating in
the motor and drive circuitry.

28

The SmartTorque feature of the LT360 automatically reduces the motor
torque to 1/2 its normal rotational power when it is not moving. Thus
providing the advantages of maximum torque when in motion and
reduced power consumption when stationary.

LT360 Precision Turntable

DLL Programming Manual

2.13 Set Acceleration Function

■ Class Set (out)

■ Identifier lt_SetAccelFunc

■ Hex Value 0x28

■ Call LT360LIB_CmdValue(Handle, lt_SetAccelFunc, 'n');

■ Parameter Function Number 0..4

Description

This command sets the acceleration function which the LT360 will use
during step or goto commands. The acceleration profile is an important
feature of the LT360 which enables heavy loads to be moved with minimum
disturbance.

The parameter string must contain a numeric value such as '1' with allowable
values from 0..4. There are five acceleration functions numbered 0,1,2,3,4.
The names of these profiles are:

LT360 Precision Turntable

0 - Impulse
1 - Flat
2 - Ramp
3 - Sin2
4 - Sin3

For most typical applications acceleration function 1 - FLAT will provide
excellent performance. Because the LT360 controls the acceleration and
deceleration so precisely, very heavy loads can be rotated with ease.

The 0 - IMPULSE function provides the fastest rise time from zero to con­stant velocity. However it also greatly reduces the maximum load which the
LT360 can rotate, due to its higher acceleration. The acceleration of this
function is about 10X that of the others.

The graphs on the following page show the velocity and acceleration profile
curves for the five different LT360 functions.

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DLL Programming Manual

0-IMPULSE

LT360 VELOCITY PROFILES

3-SIN2

2-RAMP

0-IMPULSE

3-SIN2

1-FLAT

ACCELERATION

2-RAMP

1-FLAT

4-SIN3

4-SIN3

CONSTANT VELOCITY DECELERATION

LT360 ACCELERATION PROFILES

NOTE: HEIGHT OF IMPULSE IS 10X FLAT

ACCELERATION

30

CONSTANT VELOCITY DECELERATION

LT360 Precision Turntable

DLL Programming Manual

2.14 Set Name

■ Class Set (out)

■ Identifier lt_SetName

■ Hex Value 0x29

■ Call LT360LIB_CmdValue(Handle, lt_SetName, 'xx...xx');

■ Parameter Name

Description

This command sets the Name for the LT360 unit. This is an arbitrary user
name which can be assigned to the unit. This can be useful for applications
which utilize multiple units to distinguish between the units, for example
Horz, Vert, etc. This name is stored in the LT360 and is non volatile.

The Name parameter string has a maximum length of 21 characters.

LT360 Precision Turntable

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DLL Programming Manual

2.15 Set Pulse Input

■ Class Set (out)

■ Identifier lt_SetPulseInput

■ Hex Value 0x32

■ Call LT360LIB_CmdValue(Handle, lt_SetPulseInput, 'xxx');

■ Parameter 'OFF' or 'ON'

Description

This command enables the TTL Pulse Input feature. When PulseInput is
set ON, the LT360 will respond to TTL pulses at the BNC connector.
When it is set OFF, it will ignore any pulses.

Each pulse will trigger a step. The width of the pulse should be at least
10uSec, and the triggering can be set on the rising or falling edge. Any
pulses which occur while the LT360 is moving will be ignored.

If you are not using the TTL pulse input, it is probably best to keep this
feature OFF to prevent false triggering due to any noise pickup at the
open connector.

32

LT360 Precision Turntable

DLL Programming Manual

2.16 Set Analog Input

■ Class Set (out)

■ Identifier lt_SetAnalogInput

■ Hex Value 0x33

■ Call LT360LIB_CmdValue(Handle, lt_SetAnalogInput, 'xxx');

■ Parameter 'OFF' or 'ON'

Description

This command enables the Analog Input feature. When AnalogInput is set
ON, the LT360 will respond to the DC voltage at the analog input BNC
connector. When it is set OFF, it will ignore that input.

The LT360 has a scale factor of 10mV/deg for the analog input. The range
can be either unipolar (0 ... +3.600V) or bipolar (0 ... ±1.800V). The input
impedance of the analog input is 1M Ohm. Although the input is an
unbalanced BNC connector, the actually circuitry is differential. This helps
to reject ground noise.

LT360 Precision Turntable

The input source must be very stable and of low noise. The LT360 has a
resolution of 0.1 degrees and therefore responds to changes of 1mV at the
analog input. When this input is enabled, the LT360 will sample the input
and move to the location as indicated by the voltage. After that move is
completed, it then samples the analog input again and moves to the new
position. Monitoring of the analog input is real time.

If you are not using the analog input, this input must be set OFF. Otherwise
the LT360 will be controlled by any noise received at the input.

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DLL Programming Manual

2.17 Set Display Polarity

■ Class Set (out)

■ Identifier lt_SetDisplayPolarity

■ Hex Value 0x34

■ Call LT360LIB_CmdValue(Handle, lt_SetDisplayPolarity, 'xxxxxxx');

■ Parameter 'UNIPOLAR' or 'BIPOLAR'

Description

This command changes how the LT360 represents the degree position
on the front display of the chassis, and in the Win32 software. When
DisplayPolarity is set to UNIPOLAR, the LT360 will display the position
in the range of 0 to 360 degrees. All position values are positive. When
it is set to BIPOLAR, the range will be 0 to ±180 degrees. Both positive
and negative values will be shown.

34

LT360 Precision Turntable

DLL Programming Manual

2.18 Set Input Polarity

■ Class Set (out)

■ Identifier lt_SetInputPolarity

■ Hex Value 0x35

■ Call LT360LIB_CmdValue(Handle, lt_SetInputPolarity, 'xxxxxxx');

■ Parameter 'UNIPOLAR' or 'BIPOLAR'

Description

This command changes how the LT360 interprets the DC voltage received
at the Analog Input connector. When InputPolarity is set to UNIPOLAR, the
LT360 will accept voltages in the range of 0.000 to +3.600 volts. All posi­tion values are positive. When it is set to BIPOLAR, the range will be 0.000
to ±1.800 volts. Both positive and negative values are used.

Voltages higher than the allowable range for the selected mode are invalid.

The LT360 has a scale factor of 10mV/deg for the analog input. The range
can be either unipolar (0 ... +3.600V) or bipolar (0 ... ±1.800V). The input
impedance of the analog input is 1M Ohm. Although the input is an
unbalanced BNC connector, the actually circuitry is differential. This helps
to reject ground noise.

The input source must be very stable and of low noise. The LT360 has a
resolution of 0.1 degrees and therefore responds to changes of 1mV at the
analog input. When this input is enabled, the LT360 will sample the input
and move to the location as indicated by the voltage. After that move is
completed, it then samples the analog input again and moves to the new
position. Monitoring of the analog input is real time.

If you are not using the analog input, this input must be set OFF. Otherwise
the LT360 will be controlled by any noise received at the input.

LT360 Precision Turntable

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DLL Programming Manual

2.19 Set Output Polarity

■ Class Set (out)

■ Identifier lt_SetOutputPolarity

■ Hex Value 0x36

■ Call LT360LIB_CmdValue(Handle, lt_SetOutputPolarity, 'xxxxxxx');

■ Parameter 'UNIPOLAR' or 'BIPOLAR'

Description

This command changes how the LT360 generates the DC voltage
output at the Analog Output connector. When OutputPolarity is set to
UNIPOLAR, the LT360 will produce voltages in the range of 0.000 to
+3.600 volts. All position values are positive. When it is set to BIPO­LAR, the range will be 0.000 to ±1.800 volts. Both positive and nega­tive values are produced.

The LT360 has a scale factor of 10mV/deg for the analog output. The
range can be either unipolar (0 ... +3.600V) or bipolar (0 ... ±1.800V).
The output impedance of the analog output is <200 Ohms. Although
the output is an unbalanced BNC connector, it is highly recommended
that the input on the other device be differential to reject ground noise.
Since the smallest resolution of the LT360 is 0.1 degree, the equivalent
resolution in the output is 1mV. The input impedance of the other
device should be at least 100K Ohm to prevent loading errors.

36

LT360 Precision Turntable

DLL Programming Manual

2.20 Set Move Abort

■ Class Set (out)

■ Identifier lt_SetMoveAbort

■ Hex Value 0x38

■ Call LT360LIB_CmdValue(Handle, lt_SetMoveAbort, null);

■ Parameter (none)

Description

This command can be used to terminate the rotation in progress. The LT360
will stop rotating as quickly as possible at any current location. This com­mand can be used as an emergency stop feature if needed.

LT360 Precision Turntable

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DLL Programming Manual

2.21 Set Motor Home Check

■ Class Set (out)

■ Identifier lt_SetMotorHomeChk

■ Hex Value 0x39

■ Call LT360LIB_CmdValue(Handle, lt_SetMotorHomeChk, 'xxx');

■ Parameter 'OFF' or 'ON'

Description

This command controls checking of the stepper motor synchronization .
When MotorHomeChk is set ON, the firmware checks that the motor
returns to its home position after each movement. If disabled, no
checking is performed. If checking is enabled and the motor does not
end its operation in the home position, an error message is shown on
the front panel display.

The stepper motor produces a specific number steps for a given amount
of platter rotation. The LT360 utilizes microstepping for additional
precision control. One particular phase of the motor is designated as
the Home position. For any given platter rotation, the motor should
always end in its Home position.

38

In normal operation this error should never occur. If it does, the unit
must be powered off to clear the error, or this feature disabled. It is
possible for this error to be produced by noise in the stepper motor
controller, or by the load exceeding the torque capability thereby
causing the motor to skip steps.

If this error is shown repeatedly, either there is a problem internal in the
LT360 or the torque load is too great for the drive system.

LT360 Precision Turntable

DLL Programming Manual

2.22 Set Output Mode

■ Class Set (out)

■ Identifier lt_SetOutputMode

■ Hex Value 0x3B

■ Call LT360LIB_CmdValue(Handle, lt_SetOutputMode, 'xxxx');

■ Parameter 'CONT' or 'START' or 'STOP'

Description

This command selects the operating mode for the Analog Output. The
parameter string value is either CONT or START or STOP.

When CONT is the mode, the Analog Output will continuously follow the
platter position as it is moving. This is a real time output mode where the
analog output voltage always represents the current platter position.

When START is the mode, the Analog Output will only produce a single step
change output voltage representing the final destination position at the start
of the movement. For example, if the current position is 0.0 degrees and
the destination is 100.0 degrees, the Analog Output voltage will change
from 0.000V to 1.000V at the start of the movement.

LT360 Precision Turntable

When STOP is the mode, the Analog Output will only produce a single step
change output voltage representing the final destination position after the
movement stops. For example, if the current position is 0.0 degrees and
the destination is 100.0 degrees, the Analog Output voltage will remain at

0.000V during the movement and then change to 1.000V when the move­ment stops. The final output voltage changes 2 seconds after the platter
movemet stops.

If the movement is aborted before it reaches the destination, the output
voltage will be updated to the correct final value in all modes.

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DLL Programming Manual

START

MODE

OUTPUT VOLTAGE

LT360 ANALOG OUTPUT MODES

CONT
MODE

STOP
MODE

40

PLATTER MOVEMENT

LT360 Precision Turntable

DLL Programming Manual

2.23 Get Name

■ Class Get (in)

■ Identifier lt_GetName

■ Hex Value 0x91

■ Call LT360LIB_CmdValue(Handle, lt_GetName, RtnStr);

■ Returns Name string

Description

This command returns the Name for the LT360 unit. This is an arbitrary
user name which can be assigned to the unit. This can be useful for
applications which utilize multiple units to distinguish between the units,
for example Horz, Vert, etc. This name is stored in the LT360 and is
non volatile.

The Name parameter string has a maximum length of 21 characters.

LT360 Precision Turntable

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DLL Programming Manual

2.24 Get Title

■ Class Get (in)

■ Identifier lt_GetTitle

■ Hex Value 0x92

■ Call LT360LIB_CmdValue(Handle, lt_GetTitle, RtnStr);

■ Returns 'LT360 Precision Turntable'

Description

This command returns the Title of the LT360 unit, which always is LT360
Precision Turntable. This command can be useful if you are writing your

own RS-232 program to control the LT360. This command can be used as
a test to verify that you are communicating with an LT360 unit.

42

LT360 Precision Turntable

DLL Programming Manual

2.25 Get Firmware Version

■ Class Get (in)

■ Identifier lt_GetVerCode

■ Hex Value 0x95

■ Call LT360LIB_CmdValue(Handle, lt_GetVerCode, RtnStr);

■ Returns 'n.nn'

Description

This command returns the version code of the firmware within the
LT360. For example: 1.50 The numeric value is returned as a string.

LT360 Precision Turntable

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DLL Programming Manual

2.26 Get Firmware Date

■ Class Get (in)

■ Identifier lt_GetVerDate

■ Hex Value 0x96

■ Call LT360LIB_CmdValue(Handle, lt_GetVerDate, RtnStr);

■ Returns 'mmm-dd-yyyy'

Description

This command returns the version date of the firmware within the LT360.
For example: JAN-01-2006 The date value is returned as a string.

44

LT360 Precision Turntable

DLL Programming Manual

2.27 Get Production Date

■ Class Get (in)

■ Identifier lt_GetProdDate

■ Hex Value 0x97

■ Call LT360LIB_CmdValue(Handle, lt_GetProdDate, RtnStr);

■ Returns 'mmm-dd-yyyy'

Description

This command returns the date when the LT360 was manufactured. For
example: JAN-01-2006 The date value is returned as a string.

LT360 Precision Turntable

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DLL Programming Manual

2.28 Get Calibration Date

■ Class Get (in)

■ Identifier lt_GetCalDate

■ Hex Value 0x98

■ Call LT360LIB_CmdValue(Handle, lt_GetCalDate, RtnStr);

■ Returns 'mmm-dd-yyyy'

Description

This command returns the date when the LT360 was last calibrated. For
example: JAN-01-2006 The date value is returned as a string.

Calibration is performed using the Win32 application software. Calibration
is performed originally at the factory, and in most cases will be permanent
and not be required again. It is possible for a customer to performed the
calibration, but only if the proper equipment is available. The computer
must have a GPIB bus, and two 6-1/2 digit DMMs are required themselves
with accurate recent calibration. See the LT360 Manual for further details.

46

LT360 Precision Turntable

DLL Programming Manual

2.29 Get Calibration Due

■ Class Get (in)

■ Identifier lt_GetDueDate

■ Hex Value 0x99

■ Call LT360LIB_CmdValue(Handle, lt_GetDueDate, RtnStr);

■ Returns 'mmm-dd-yyyy'

Description

This command returns the date when the LT360 should be re-calibrated.
For example: JAN-01-2007 The date value is returned as a string.

Calibration is performed using the Win32 application software. Calibra­tion is performed originally at the factory, and in most cases will be
permanent and not be required again. However if your application
requires NIST compliance, this is the date when the LT360 should be
rechecked. It is possible for a customer or other lab to performed the
calibration, but only if the proper equipment is available. The computer
must have a GPIB bus, and two 6-1/2 digit DMMs are required them­selves with accurate recent calibration. See the LT360 Manual for
further details.

LT360 Precision Turntable

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DLL Programming Manual

2.30 Get Serial Number

■ Class Get (in)

■ Identifier lt_GetSerialNum

■ Hex Value 0x9A

■ Call LT360LIB_CmdValue(Handle, lt_GetSerialNum, RtnStr);

■ Returns 'nnnnnn'

Description

This command returns the serial number of the LT360 unit. The number is
returned as a string value of 6 digits.

48

LT360 Precision Turntable

DLL Programming Manual

2.31 Get Baud Rate

■ Class Get (in)

■ Identifier lt_GetBaudRate

■ Hex Value 0x9B

■ Call LT360LIB_CmdValue(Handle, lt_GetBaudRate, RtnStr);

■ Returns 'nnnnn'

Description

This command returns the current baud rate the LT360 is using. The
number is returned as a string value of 4-6 digits.

LT360 Precision Turntable

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DLL Programming Manual

2.32 Get Position

■ Class Get (in)

■ Identifier lt_GetPosition

■ Hex Value 0x9C

■ Call LT360LIB_CmdValue(Handle, lt_GetPosition, RtnStr);

■ Returns '±nnn.n'

Description

This command returns the current position of the LT360 in degrees. The
value is returned as a string with tenths of degree precision. The value may
be 0 to +360.0 or 0 to ±180.0 depending on the settings for the display
polarity.

This command is very useful when you want to know the current position of
the LT360, or if the LT360 has completed a movement. It can be used in a
polling loop to see when the LT360 step or goto command has finished.
Another alternative method would be to call the Get Moving command until
the NO value is returned.

50

When using either method in a polling loop, the frequency of calls should be
reasonable. Typically, testing for movement completion once every second
is more than adequate.

LT360 Precision Turntable

DLL Programming Manual

2.33 Get Pulse Direction

■ Class Get (in)

■ Identifier lt_GetPulseDir

■ Hex Value 0x9D

■ Call LT360LIB_CmdValue(Handle, lt_GetPulseDir, RtnStr);

■ Returns 'CCW' or 'CW'

Description

This command returns the setting for the Pulse Direction. The value is
returned as either CCW (counter clockwise) or CW (clockwise). This
parameter controls the behavior to a TTL step pulse at the Pulse input
BNC connector.

When a pulse arrives at the Pulse BNC input, the platter will rotate
either CCW or CW as defined by this setting. The size of the step is
controlled by the Set StepSize command.

LT360 Precision Turntable

Note: The TTL pulse should be a minimum of 10uS, or longer. The
triggering edge can be controlled by the Set PulseEdge command.

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DLL Programming Manual

2.34 Get Pulse Edge

■ Class Get (in)

■ Identifier lt_GetPulseEdge

■ Hex Value 0x9E

■ Call LT360LIB_CmdValue(Handle, lt_GetPulseEdge, RtnStr);

■ Returns 'RISE' or 'FALL'

Description

This command returns the setting for the Pulse Edge triggering. The value is
returned as either RISE (rising edge) or FALL (falling edge). This parameter
controls the behavior to a TTL step pulse at the Pulse input BNC connector.

When a pulse arrives at the Pulse BNC input, the platter will rotate either at
the rising or falling edge as defined by this setting. The size of the step is
controlled by the Set StepSize command.

Note: The TTL pulse should be a minimum of 10uS, or longer. The direction
can be controlled by the Set PulseDir command.

52

LT360 Precision Turntable

DLL Programming Manual

2.35 Get Step Size

■ Class Get (in)

■ Identifier lt_GetStepSize

■ Hex Value 0x9F

■ Call LT360LIB_CmdValue(Handle, lt_GetStepSize, RtnStr);

■ Returns 'nnn.n'

Description

This command returns the step size value. The value is returned as a
string with tenths of a degree precision, and is always positive. This
value sets the angular step size by which the platter will rotate to either
a step command or TTL pulse.

The minimum step size is 0.1 degrees. Step size is always positive.
Direction is controlled by the CCW/CW commands listed else where.

LT360 Precision Turntable

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DLL Programming Manual

2.36 Get Velocity

■ Class Get (in)

■ Identifier lt_GetVelocity

■ Hex Value 0xA0

■ Call LT360LIB_CmdValue(Handle, lt_GetVelocity, RtnStr);

■ Returns 'n.nn'

Description

This command returns the velocity in RPM (revolutions per minute). The
value is returned as a string with hundreths precision, and is always positive.
The allowable range for the parameter is 0.01 to 3.00 RPM.

54

LT360 Precision Turntable

DLL Programming Manual

2.37 Get Torque

■ Class Get (in)

■ Identifier lt_GetTorque

■ Hex Value 0xA1

■ Call LT360LIB_CmdValue(Handle, lt_GetTorque, RtnStr);

■ Returns 'nnn.n'

Description

This command returns the torque in percent (%). The value is returned
as a string with tenths precision, and is always positive. The allowable
range for the parameter is 10.0 to 100.0 %.

This value sets the stepper motor torque for the platter rotation. The
value is set in percent of maximum torque. For most typical applica­tions your will want the torque set to 100%. If you intend to have the
platter in constant motion, than you may wish to set the torque to a
lower value such as 70%. This will reduce heating in the motor and
drive circuitry.

LT360 Precision Turntable

The SmartTorque feature of the LT360 automatically reduces the motor
torque to 1/2 its normal rotational power when it is not moving. Thus
providing the advantages of maximum torque when in motion and
reduced power consumption when stationary.

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DLL Programming Manual

2.38 Get Acceleration Function

■ Class Get (in)

■ Identifier lt_GetAccelFunc

■ Hex Value 0xA2

■ Call LT360LIB_CmdValue(Handle, lt_GetAccelFunc, RtnStr);

■ Returns 'n'

Description

This command returns the acceleration function number (0 to 4). This value
gives the acceleration function which the LT360 will use during step or goto
commands. The acceleration profile is an important feature of the LT360
which enables heavy loads to be moved with minimum disturbance.

The parameter string contains a numeric value such as '1' with allowable
values from 0..4. There are five acceleration functions numbered 0,1,2,3,4.
The names of these profiles are:

56

0 - Impulse
1 - Flat
2 - Ramp
3 - Sin2
4 - Sin3

For most typical applications acceleration function 1 - FLAT will provide
excellent performance. Because the LT360 controls the acceleration and
deceleration so precisely, very heavy loads can be rotated with ease.

The 0 - IMPULSE function provides the fastest rise time from zero to con­stant velocity. However it also greatly reduces the maximum load which the
LT360 can rotate, due to its higher acceleration. The acceleration of this
function is about 10X that of the others.

The graphs on the following page show the velocity and acceleration profile
curves for the five different LT360 functions.

LT360 Precision Turntable

0-IMPULSE

DLL Programming Manual

LT360 VELOCITY PROFILES

3-SIN2

2-RAMP

0-IMPULSE

3-SIN2

1-FLAT

ACCELERATION

2-RAMP

1-FLAT

4-SIN3

4-SIN3

CONSTANT VELOCITY DECELERATION

LT360 ACCELERATION PROFILES

NOTE: HEIGHT OF IMPULSE IS 10X FLAT

ACCELERATION

LT360 Precision Turntable

CONSTANT VELOCITY DECELERATION

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DLL Programming Manual

2.39 Get Moving

■ Class Get (in)

■ Identifier lt_GetMoving

■ Hex Value 0xA3

■ Call LT360LIB_CmdValue(Handle, lt_GetMoving, RtnStr);

■ Returns 'CCW' or 'CW' or 'NO'

Description

This command returns the rotational status of the LT360. Three possible
string values can be returned:

CCW - rotating counter clockwise
CW - rotating clockwise
NO - not rotating

This command is very useful when you want to know if the LT360 has
completed a movement. It can be used in a polling loop to see when the
LT360 step or goto command has finished. Another alternative method
would be to call the Get Position command until the desired location is
returned.

58

When using either method in a polling loop, the frequency of calls should be
reasonable. Typically, testing for movement completion once every second
is more than adequate.

LT360 Precision Turntable

DLL Programming Manual

2.40 Get Pulse Input

■ Class Get (in)

■ Identifier lt_GetPulseInput

■ Hex Value 0xA9

■ Call LT360LIB_CmdValue(Handle, lt_GetPulseInput, RtnStr);

■ Returns 'OFF' or 'ON'

Description

This command returns the status for the Pulse Input BNC function of the
LT360. The returned string value is either OFF or ON.

This parameter enables the TTL Pulse Input feature. When PulseInput is set
ON, the LT360 will respond to TTL pulses at the BNC connector. When it is
set OFF, it will ignore any pulses.

Each pulse will trigger a step. The width of the pulse should be at least
10uSec, and the triggering can be set on the rising or falling edge. Any
pulses which occur while the LT360 is moving will be ignored.

LT360 Precision Turntable

If you are not using the TTL pulse input, it is probably best to keep this
feature OFF to prevent false triggering due to any noise pickup at the open
connector.

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DLL Programming Manual

2.41 Get Analog Input

■ Class Get (in)

■ Identifier lt_GetAnalogInput

■ Hex Value 0xAA

■ Call LT360LIB_CmdValue(Handle, lt_GetAnalogInput, RtnStr);

■ Returns 'OFF' or 'ON'

Description

This command returns the status for the Analog Input BNC function of the
LT360. The returned string value is either OFF or ON.

This parameter enables the Analog Input feature. When AnalogInput is set
ON, the LT360 will respond to the DC voltage at the analog input BNC
connector. When it is set OFF, it will ignore that input.

The LT360 has a scale factor of 10mV/deg for the analog input. The range
can be either unipolar (0 ... +3.600V) or bipolar (0 ... ±1.800V). The input
impedance of the analog input is 1M Ohm. Although the input is an
unbalanced BNC connector, the actually circuitry is differential. This helps
to reject ground noise.

60

The input source must be very stable and of low noise. The LT360 has a
resolution of 0.1 degrees and therefore responds to changes of 1mV at the
analog input. When this input is enabled, the LT360 will sample the input
and move to the location as indicated by the voltage. After that move is
completed, it then samples the analog input again and moves to the new
position. Monitoring of the analog input is real time.

If you are not using the analog input, this input must be set OFF. Other­wise the LT360 will be controlled by any noise received at the input.

LT360 Precision Turntable

DLL Programming Manual

2.42 Get Smart Torque

■ Class Get (in)

■ Identifier lt_GetSmartTorque

■ Hex Value 0xAB

■ Call LT360LIB_CmdValue(Handle, lt_GetSmartTorque, RtnStr);

■ Returns 'OFF' or 'ON'

Description

This command returns the status for the Smart Torque feature of the LT360.
The returned string value is either OFF or ON.

This parameter controls the behavior of the stepper motor. When
SmartTorque is set ON, the motor is powered down to half the driving
power 2 seconds after each movement stops. Motor power is returned to
full (as controlled by the Maximum Torque setting) when the motor starts
again.

LT360 Precision Turntable

This feature takes advantage of the fact that the worm gear drive system
employed by the LT360 is irreversible. Meaning, the platter is self-locking at
its current position. The load cannot rotate the platter itself. Therefore, it is
not necessary to maintain full power on the motor merely to hold its current
position when the platter is not in movement.

The use of SmartTorque greatly reduces the thermal heating in the motor
and driver circuitry, and produces a very efficient drive system. Under most
conditions and use, this feature should always be kept ON.

If a particular application demands that the motor power be kept constant at
all times, even when stationary (SmartTorque=OFF), then the maximum
torque should be to 70% or less to prevent excessive heating. It is difficult
to envision what kinds of applications would require this behavior, but the
option is available if needed.

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DLL Programming Manual

2.43 Get Display Polarity

■ Class Get (in)

■ Identifier lt_GetDisplayPolarity

■ Hex Value 0xAC

■ Call LT360LIB_CmdValue(Handle, lt_GetDisplayPolarity, RtnStr);

■ Returns 'UNIPOLAR' or 'BIPOLAR'

Description

This command returns the mode for the Display Polarity of the LT360.
The returned string value is either UNIPOLAR or BIPOLAR.

This parameter changes how the LT360 represents the degree position
on the front display of the chassis, and in the Win32 software. When
DisplayPolarity is set to UNIPOLAR, the LT360 will display the position
in the range of 0 to 360 degrees. All position values are positive. When
it is set to BIPOLAR, the range will be 0 to ±180 degrees. Both positive
and negative values will be shown.

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LT360 Precision Turntable

DLL Programming Manual

2.44 Get Input Polarity

■ Class Get (in)

■ Identifier lt_GetInputPolarity

■ Hex Value 0xAD

■ Call LT360LIB_CmdValue(Handle, lt_GetInputPolarity, RtnStr);

■ Returns 'UNIPOLAR' or 'BIPOLAR'

Description

This command returns the mode for the Analog Input Polarity of the LT360.
The returned string value is either UNIPOLAR or BIPOLAR.

This parameter changes how the LT360 interprets the DC voltage received
at the Analog Input connector. When InputPolarity is set to UNIPOLAR, the
LT360 will accept voltages in the range of 0.000 to +3.600 volts. All posi­tion values are positive. When it is set to BIPOLAR, the range will be 0.000
to ±1.800 volts. Both positive and negative values are used.

LT360 Precision Turntable

Voltages higher than the allowable range for the selected mode are invalid.

The LT360 has a scale factor of 10mV/deg for the analog input. The range
can be either unipolar (0 ... +3.600V) or bipolar (0 ... ±1.800V). The input
impedance of the analog input is 1M Ohm. Although the input is an
unbalanced BNC connector, the actually circuitry is differential. This helps
to reject ground noise.

The input source must be very stable and of low noise. The LT360 has a
resolution of 0.1 degrees and therefore responds to changes of 1mV at the
analog input. When this input is enabled, the LT360 will sample the input
and move to the location as indicated by the voltage. After that move is
completed, it then samples the analog input again and moves to the new
position. Monitoring of the analog input is real time.

If you are not using the analog input, this input must be set OFF. Otherwise
the LT360 will be controlled by any noise received at the input.

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DLL Programming Manual

2.45 Get Output Polarity

■ Class Get (in)

■ Identifier lt_GetOutputPolarity

■ Hex Value 0xAE

■ Call LT360LIB_CmdValue(Handle, lt_GetOutputPolarity, RtnStr);

■ Returns 'UNIPOLAR' or 'BIPOLAR'

Description

This command returns the mode for the Analog Output Polarity of the
LT360. The returned string value is either UNIPOLAR or BIPOLAR.

This parameter changes how the LT360 generates the DC voltage
output at the Analog Output connector. When OutputPolarity is set to
UNIPOLAR, the LT360 will produce voltages in the range of 0.000 to
+3.600 volts. All position values are positive. When it is set to BIPO­LAR, the range will be 0.000 to ±1.800 volts. Both positive and nega­tive values are produced.

64

The LT360 has a scale factor of 10mV/deg for the analog output. The
range can be either unipolar (0 ... +3.600V) or bipolar (0 ... ±1.800V).
The output impedance of the analog output is <200 Ohms. Although
the output is an unbalanced BNC connector, it is highly recommended
that the input on the other device be differential to reject ground noise.
Since the smallest resolution of the LT360 is 0.1 degree, the equivalent
resolution in the output is 1mV. The input impedance of the other
device should be at least 100K Ohm to prevent loading errors.

LT360 Precision Turntable

DLL Programming Manual

2.46 Get Motor Home Check

■ Class Get (in)

■ Identifier lt_GetMotorHomeChk

■ Hex Value 0xC1

■ Call LT360LIB_CmdValue(Handle, lt_GetMotorHomeChk, RtnStr);

■ Returns 'OFF' or 'ON'

Description

This command returns the status for checking stepper motor synchroniza­tion. The returned string value is either OFF or ON.

When MotorHomeChk is set ON, the firmware checks that the motor
returns to its home position after each movement. If disabled, no checking
is performed. If checking is enabled and the motor does not end its opera­tion in the Home position, an error message is shown on the front panel
display.

LT360 Precision Turntable

The stepper motor produces a specific number steps for a given amount of
platter rotation. The LT360 utilizes microstepping for additional precision
control. One particular phase of the motor is designated as the Home
position. For any given platter rotation, the motor should always end in its
Home position.

In normal operation this error should never occur. If it does, the unit must
be powered off to clear the error, or this feature disabled. It is possible for
this error to be produced by noise in the stepper motor controller, or by the
load exceeding the torque capability thereby causing the motor to skip
steps.

If this error is shown repeatedly, either there is a problem internal in the
LT360 or the torque load is too great for the drive system.

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DLL Programming Manual

2.47 Get Revision Code

■ Class Get (in)

■ Identifier lt_GetRevCode

■ Hex Value 0xC2

■ Call LT360LIB_CmdValue(Handle, lt_GetRevCode, RtnStr);

■ Returns 'nn' ASCII code of chr

Description

This command returns the revision code of the controller PC board, as
an ASCII code for the revision letter. For example, '65' = A.

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LT360 Precision Turntable

DLL Programming Manual

2.48 Get Output Mode

■ Class Get (in)

■ Identifier lt_GetOutputMode

■ Hex Value 0xC3

■ Call LT360LIB_CmdValue(Handle, lt_GetOutputMode, RtnStr);

■ Returns 'CONT' or 'START' or 'STOP'

Description

This command returns the operating mode for the Analog Output. The
returned string value is either CONT or START or STOP.

When CONT is the mode, the Analog Output will continuously follow the
platter position as it is moving. This is a real time output mode where the
analog output voltage always represents the current platter position.

When START is the mode, the Analog Output will only produce a single step
change output voltage representing the final destination position at the start
of the movement. For example, if the current position is 0.0 degrees and
the destination is 100.0 degrees, the Analog Output voltage will change
from 0.000V to 1.000V at the start of the movement.

LT360 Precision Turntable

When STOP is the mode, the Analog Output will only produce a single step
change output voltage representing the final destination position after the
movement stops. For example, if the current position is 0.0 degrees and
the destination is 100.0 degrees, the Analog Output voltage will remain at

0.000V during the movement and then change to 1.000V when the move­ment stops. The final output voltage changes 2 seconds after the platter
movemet stops.

If the movement is aborted before it reaches the destination, the output
voltage will be updated to the correct final value in all modes.

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DLL Programming Manual

START

MODE

OUTPUT VOLTAGE

LT360 ANALOG OUTPUT MODES

CONT
MODE

PLATTER MOVEMENT

STOP
MODE

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LT360 Precision Turntable