MTS Systems Temposonics II LDT Quick guide

1
l
Sensors Division
Temposonics®II
Linear Displacement Transducer
Installation and Instruction Manual for
DIGITAL SYSTEMS
P/N 550033 Rev. F
Part No. 550033 Rev. E

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GENERAL INFORMATION
MTS PHONE NUMBERS
Application questions: 800-633-7609
Service: 800-248-0532
Fax: [phone]
SHIPPING ADDRESS
MTS Systems Corporation
Sensors Division
3001 Sheldon Drive
Cary, North Carolina 27513
HOURS
Monday - Thursday
7:30 a.m. to 6:30 p.m. EST/EDT
Friday
7:30 a.m. to 5:00 p.m. EST/EDT

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TABLE OF CONTENTS
Section Page
1 INTRODUCTION 1
1.1 Theory of Operation/Magnetostriction 1
1.2 Temposonics II LDT Specifications 2
1.3 Specifications for Temposonics II LDTs over 180 inches 3
2 TEMPOSONICS II LDT INSTALLATION 4
2.1 Types of Transducer Supports 6
2.1.1 Loop Supports 6
2.1.2 Channel Supports 7
2.1.3 Guide Pipe Supports 7
2.2 Open Magnets 8
2.3 Spring Loading and Tensioning 8
2.4 Cylinder Installation 8
2.5 Installing Magnets 11
3 GROUNDING 12
4 DIGITAL SYSTEM CONFIGURATIONS 13
4.1 Specifications of Digital System Components 14
4.2 Digital Personality Module 15
4.2.1 Synchronous (External Interrogating) Mode 15
4.2.2 Asynchronous (Internal Interrogating) Mode 16
4.2.3 Operation During Loss of Signal 16
4.3 RS422 Personality Module 17
4.4 Digital Counter Card 18
4.4.1 Scaling 19
4.4.2 Spare Parts/Inventory Considerations 19
5 DIGITAL SYSTEM ADJUSTMENTS 20
6 ELECTRONIC CONNECTIONS 21
6.1 General 21
6.2 Transducer Connections 22
6.3 Digital Counter Card Connections 24
6.3.1 Latch Pulse 25
6.3.2 Protocol 25
6.3.3 Latch Inhibit Input 25
6.4 Counter Cards - Natural Binary Output 26
6.5 Counter Cards - BCD Output 29
6.6 System Calibration 32
6.6.1 Re-zeroing the Digital Counter Card 32
6.6.2 Scaling the Digital Counter Card 37
APPENDICES
A How to Specify Systems with Digital Output 38
B Digital Personality Module (DPM) Programming Procedure (Asynchronous Mode) 45
C Modification to the Digital Interface Box 49
D Troubleshooting 51

1
1. Introduction to the Temposonics II Linear Displacement Transducer (LDT)
The Temposonics II LDT precisely senses the position of an external magnet to measure displacement with a high
degree of accuracy and resolution. Using the principle of magnetostriction (see Section 1.1, below), the
Temposonics II LDT measures the time interval between the initiation of an interrogation pulse and the detection
of a return pulse. A variety of interface devices use the data derived from these two pulses and generates an ana-
log or digital output to represent position.
1.1 Theory of Operation/Magnetostriction
The interrogation pulse travels the length of the transducer by a conducting wire threaded through a hol-
low waveguide. The waveguide is spring loaded within the transducer rod and exhibits the physical prop-
erty of magnetostriction. When the magnetic field of the interrogation pulse interacts with the stationary
magnetic field of the external magnet, a torsional strain pulse or “twist” is produced in the waveguide.
This strain pulse travels in both directions, away from the magnet. At the end of the rod, the strain pulse
is damped within the “dead zone” (2.5 inches in length). At the head of the transducer, two magnetically
coupled sensing coils are attached to strain sensitive tapes. The tapes translate the strain pulse through
coils to an electrical “return pulse”. The coil voltage is then amplified in the head electronics before it is
sent to various measuring devices as the conditioned “return pulse”.
Figure 1-1
Waveguide Interaction
Reference
magnetic field
Conducting element
Interaction of magnetic
fields causes
waveguide to twist
Magnetic field from interrogation pulse
Waveguide
twist
Waveguide Sensing coil
Bias magnet
Strain tape
External reference magnet
Waveguide enclosure

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1.2 Temposonics II LDT Specifications
Parameter Specifications
Input Voltage: ± 12 to ± 15 Vdc
Current Draw: Transducer Only:
± 15 Vdc at 100 mA maximum, 25 mA minimum
(current draw varies with magnet position, maximum draw occurs when magnet is at 2 in.
(50.6 mm) from the flange and minimum update time is being utilized)
Transducer with:
• RS-422 Personality Module (RPM): ± 12 to ±15 Vdc at 140 mA maximum
• Digital Personality Module (DPM): + 15 Vdc at 150 mA maximum, 75 mA minimum, - 15 Vdc
at 100 mA maximum, 25 mA minimum
Displacement: Up to 25 feet (7620 millimeters)
Dead Space: 2.5 inches (63.5 millimeters) for stroke lengths up to 179.9 in.
3 inches (76.2 millimeters) for stroke lengths ≥180 in.
Electronics Enclosure: IP-67
Non-linearity: < ± 0.05% of full scale or ± 0.002 inch (±0.05 mm), whichever is greater
Resolution: 1 ÷ [gradient x crystal freq. (mHz) x circulation]; maximum resolution: 0.006 mm or 0.00025 in.
Repeatability: Equals resolution
Hysteresis: 0.0008 inch (0.02 mm) maximum
Update Time: Resolution and Stroke dependent
Minimum = [Stroke (specified in inches) + 3] x 9.1 µs
Operating Temperature
Head Electronics: - 40 to 150°F (- 40 to 66°C)
Transducer Rod: - 40 to 185°F (- 40 to 85°C)
Operating Pressure: 3000 psi continuous, 8000 psi static
Digital Outputs (absolute) TTL level, nominal 0 and 5V, true high, parallel transmission
Specifications are subject to change without notice. Consult MTS for verification of specifications critical to your application.

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1.3 Specifications for Temposonics II LDTs over 180 Inches
Below is a list of specifications that pertain to Temposonics II transducers with active stroke lengths of
180 inches (4572 mm) to 300 inches (7620 mm). Special versions of the Analog Output Modules (AOM)
and Digital Interface Boxes (DIB) are required to interface with transducers over 180 inches in length.
Contact an MTS Applications Engineer for details before ordering.
Parameter Specification
Parameter Specifications
Input Voltage: • Maximum: ± 15 Vdc, ± 5% at 100 mA
• Minimum: ± 15 Vdc at 25 mA
(current draw varies with magnet position, maximum draw occurs when magnet is 2 inches
(50.8 mm) from the flange and minimum update time is being used)
Dead Space: 3 in. (76.2 mm)
Cable Length: • Maximum cable length for neuter version transducer (i.e., Temposonics II without an
integrated Personality Module) which requires the use of external interface electronics
(Analog output Module, Digital Interface Box or other signal conditioners) is 250 ft.
• Maximum cable length for Temposonics II transducers with Personality Modules
RPM: 1640 feet (500 meters) using external interrogation
DPM: 300 feet (90 meters) using external interrogation
Magnet Requirement: Part Number: 201554 or 201553 ONLY

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2. Temposonics II LDT Installation
Before beginning installation, be sure you know the following dimensions (as illustrated in Figures 2-1 to 2-3a-c.):
• Null Space
• Stroke
• Dead Zone
Figure 2-1
Temposonics II Dimension
Figure 2-2
Temposonics II Connector/Cable Clearance Requirements
Temposonics II with
Molded Connector/Cable Assembly
Temposonics II with
Field Instalable Connector
Temposonics II with
Integral Cable
2.5 in. minimum
(clearance for connector
and cable bend)
1.25 in.
minimum
3/4-16 UNF-3A Thread
0.38 in. DIA
(9.65 mm)
Standard Null
(2.0 in., 50 mm)
0.38 in. (9.65 mm)
1.36 in.
(34.54 mm)
End Plug,
Flush 0.83 in.
(9.65 mm)
0.03 in. (0.76 mm)
Hex
1.75 in. (44.45 mm) across flats
2.13 in.
(54 mm)
Flange to Tip
Stroke Length
(specified by customer)
1.57 in. dia.
(39.87 mm)
1.75 in. dia.
(44.45 mm)
2.50 in.
(63.50 mm)
Dead Zone
2.50 in.
(63.50 mm)
for stroke
lengths up to
179.9 in;
3 in. (76.2 mm)
for strokes
≥180 in.

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1. Use the 3/4 inch (19 mm), 16 UNF thread of the transducer to mount it at the selected location. Leave room to
access the hex head. If a pressure or moisture seal is required, install an O-ring (type MS 28778-8 is recom-
mended) in the special groove. Use the hex head to tighten the transducer assembly.
2. Install the permanent magnet over the LDT rod. Mount the permanent magnet to the movable device whose
displacement will be measured. To minimize the effect of magnetic materials (i.e. iron, steel, etc.) on the mag-
netic field of the permanent magnet, ensure the minimum spacing requirements are met as shown in Figure 2-
4. (Any non-magnetic materials can be in direct contact with the permanent magnet without affecting perfor-
mance.)
Figure 2-3a
Minimum Magnet Clearance Using Magnetic Supports
Figure 2-3b Figure 2-3c
Minimum Null Space Using Non-Magnetic Support Minimum Null Space Using Magnetic Support
Notes:
1. The magnet must not contact ferromagnetic materials (such as iron or steel). Clearances are required between the surface of the magnet
and ferromagnetic material, as shown. Non-ferrous material (such as copper, brass, or 300 series stainless steel) may contact the magnet
without affecting transducer performance.
2. Standard Null Space is 2 inches. There is no maximum limit for Null Space. Less then 2 inches can be specified if magnet clearances meet
requirements illustrated above.
5/8 in.
Minimum
Ferromagnetic Support
Magnet
A = 5/8 in. plus support thickness
A
NON-Ferromagnetic Support
Magnet
A = 1 in., minimum to clear threads
Threads
A
1/8 in.
Minimum 5/8 in. Minimum
Magnet
Tip Head
Ferromagnetic Material

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4. Move the permanent magnet full-scale to check that it moves freely. If not (if the magnet rubs on the transduc-
er) you can correct this by mounting a support bracket to the end of the transducer. Long transducers may
need additional supports to be attached to the transducer rod. Transducer supports are described later in this
section.
2.1 Types of Transducer Supports
Long transducers (48 inches or longer) may require supports to maintain proper alignment between the
transducer rod and the permanent magnet. When transducer rod supports are used, special, open-ended
permanent magnets are required.
Transducer supports attached to the active stroke length must be made of a non-ferrous material, thin
enough to permit the permanent magnet to pass without obstruction. Because the permanent magnet
does not enter the dead zone, supports connected within the dead zone may be made of any material.
The main types of supports are loop, channel, and guide pipe supports.
2.1.1 Loop Supports
Loop supports are fabricated from non-ferrous materials, thin enough to permit free movement of
the magnet. Loop supports are recommended for straight transducers. They may be used alone or
with channel supports. Figure 2-4 illustrates the fabrication of a loop support.
Figure 2-4
Loop Support
NOTE:
When open magnets are used, ensure the
transducer rod remains within the inside
diameter of the magnet throughout the
length of the stroke. If the transducer rod
is allowed to enter the cut out area of an
open magnet, the transducer signal
could attenuate or be lost. See Figure 2-7.
TransducerRod
0.375in.
I.D.
FrontView
Side View
NOTE:
Clearance between the magnet and the
transducer rod is not critical. However,
contact between the components will
cause wear over time. The installation of
supports or readjustment of the supports
is recommended if the magnet contacts
the transducer rod.

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2.1.2 Channel Supports
Channel supports, being typically straight, are normally used with rigid transducers. A channel
support consists of a straight channel with loop supports mounted at intervals. The loop supports
are required to keep the transducer within the channel. Figure 2-5 shows a channel support.
Channel supports are available from various manufacturers or may be fabricated.
Figure 2-5
Channel Support
2.1.3 Guide Pipe Supports
Guide pipe supports are normally used for flexible transducers. A guide pipe support is construct-
ed of non-ferrous material, straight or bent to the desired shape. As shown in Figure 2-6, both
inside and outside dimensions of the pipe are critical:
• Because the transducer rod is installed inside the pipe, the inside diameter of the pipe must be
large enough to clear the rod.
Figure. 2-6
Guide Pipe Support
• The outside diameter of the pipe must be small enough to clear the magnet.
Refer to pipe manufacturers’ specifications and dimensions (schedule 10, 40, etc.) to select the
appropriate size pipe. Guide pipe is typically supported at each end of the pipe.
Magnet
• Part No.: 201553 or
• Part No.: 251416
Guide Pipe
Rod
Magnet
• Part No.: 201553 or
• Part No.: 251416
Loop Support
Rod

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2.2 Open Magnets
When using an open magnet, make sure the rod is positioned at all times within the “active” zone of the
magnet. The transducer cannot operate properly unless the entire stroke of the transducer rod is located
within this zone. The active zone, as shown in Figure 2-7, lies within the inside diameter of the magnet.
Figure 2-7
Active Zone for Open Magnets
2.3 Spring Loading or Tensioning
The transducer rod (flexible or rigid) can be spring loaded or tensioned using a stationary weight. Attach
a spring mechanism or weight to the dead zone of the transducer rod with a clamping device which will
not deform the transducer rod. The maximum weight or spring tension is 5 to 7 lbs.
2.4 Cylinder Installation
Figure 2-8
Typical Cylinder Installation
Null (as specified)
Minimum: 2 in. (50mm)
NON-ferrous Spacer, Part No.: 400633
Magnet, Type SR-12
Part No.: 201542
(1.29 in. (32.76 mm) O.D.
(other options available)
Chamfered Rod Bushing
1
5
Nylok® Insert 6
2
O-ring (MS 28778-8 or equivalent)
Part No.: 560315
Piston Head and Rod Assembly
4
0.5 in (12.7 mm) Bore
Active Stroke3
Minimum: 5 in. (127 mm)
Dead Zone:
2.50 in. (63.5 mm)
for stroke lengths
up to 179.9 in;
3 in. (76.2 mm)
for stroke lengths
≥180 in.
Active
Zone
InactiveZone

9
Figure 2-8 shows a typical cylinder installation. Review the following before attempting this type of instal-
lation.
• Use a non-ferrous (plastic, brass, Teflon®, etc.) spacer [1] to provide 1/8 inch (32 mm) minimum space
between the magnet and the piston.
• An O-ring groove [2] is provided at the base of the transducer hex head for pressure sealing. MTS uses
mil-standard MS33514 for the O-ring groove. Refer to mil-standard MS33649 or SAE J514 for machining
of mating surfaces.
• The null space [3] is specified according to the installation design and cylinder dimensions. The analog
output module provides a null adjustment. Make sure that the magnet can be mounted at the proper
null position.
• The piston head [4] shown in Figure 2-8 is typical. For some installations, depending on the clearances,
it may be desired to countersink the magnet.
• A chamfered rod bushing [5] should be considered for stokes over 5 feet (1.5 meters) to prevent wear
on the magnet as the piston retracts. The bushing should be made from Teflon or similar material.
• A Nylok self locking insert [6] is provided on the transducer threads. An O-ring groove is provided at
the base of the transducer hex head for pressure sealing.
• The recommended bore for the cylinder rod is 1/2 inch (13 mm). The transducer rod includes a 0.375
inch flush (9.53 mm) end plug. Use standard industry practices for machining and mounting of all com-
ponents. Consult the cylinder manufacturer for applicable SAE or military specifications.
Figure 2-9a
O-ring Boss Detail
2.250 in. Minimum Dia
Specifies Surface B
0.875 in. Dia.
+.0.015
-0.000
0.769 in. Dia.
+.0.015
-0.000
120°±0°30'
0.094 in. +.0.015
-0.000
1.105 in.
Minimum
Full Thread
Depth See Detail C
3/4-16 UNIF-3B Thread
See Notes 3 And 4
0.500
Dia.
Blind Thread Design 45°±5°
See Note 7
See Detail C
3/4-16 UNJF-3B Thread
See Notes 3 and 4
Thru Thread Design
120°±0°30'
2.250 in. Minimum Dia
Specifies Surface B
0.094 in. REF
See Note 8
0.030 in. ±0.010 R
Detail C
NOTES:
1. Dimensions and tolerances based on ANSI Y14.5-1982.
2. MTS has extracted all pertinent information from MS33649 to Generate this document.
3. PD must be square with surface B within 0.005 FIM across 2.250 dia minimum.
4. PD must be concentric with 2.250 dia within 0.030 FIM and with 0.769 dia within 0.005 FIM.
5. Surface texture ANSI B46.1-1978
6. Use o-ring MTS part number 560315 for correct sealing.
7. The thread design shall have sufficient threads to meet strength requirements of material used.
8. Finish counter-bore shall be free from longitudinal and spiral tool marks. Annular tool marks up to 32 micro-
inches maximum will be permissible.
Key:
FIM=FullIndicatorMovement
PD = Pitch Diameter
0.020 in. R
Maximum
32 µin.
32 µin.
125 µin. 125 µin.
0.875in. Dia.
+.0.015
-0.000
0.769in. Dia.
+.0.015
-0.000
32 µin.
32 µin.
0.094in. +.0.015
-0.000
- B - - B -
0.005 in. Dia., FIMA 0.005 in. Dia., FIMA

10
Figure 2-9b
Port Detail (SAE J1926/1)
NOTES:
1. If face of port is on a machined surface, dimensions 1.180 and 0.094 need not apply as
long as R0.008/0.004 is maintained to avoid damage to the O-ring during installation.
2. Measure perpendicularity to A at this diameter.
3. This dimension applies when tap drill cannot pass through entire boss.
4. This dimension does not conform to SAE J1926/1.
1.100 in.
See Note 4 1.250 in.
See Note 3
See Note 4
ø0.500 in.
Ref.
See Note 4
1.180 in.
Recommended
Minimum
Spotface
Diameter
See Note 1
45°±5°
15°±1°
0.094 in. Max.
R0.015 in.
Max.
0.008 in.
0.004 in.
Pitch
Dia.
0.125 µin.
0.125 µin.
3/4-16 UNF-2B Thread
ø0.866in.
Minimum
See Note 2
R
ø0.813 in.
±0.002 in.
0.106 in.
±0.008 in.
A
0.008 A
0.004 A

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2.5 Installing Magnets
Figure 2-10 below shows the standard magnet types and dimensions. The circular magnet with an outside
diameter of 1.29 inches and 0.53 inch inside diameter (Part No. 201542) is the most common and is suit-
able for most applications. Larger magnets, with an outside diameter of 2.5 inches are typically only used
with Temposonics transducers that exceed 180 inches in stroke length. Magnets with a 90 degree cut-out
are used in applications that require intermediate supports along the transducer rod.
If upon installation, the null adjustment is inadequate, you can design a coupler with adjustments to
mount the magnet to the measured member.
Figure 2-10
Magnet Dimensions
Part No. 201554
1 of 4 holes
each 0.182 in. dia. (4.6 mm)
on 1.625 in. dia. (41.3 mm)
I.D.: 0.75 in. (19.05 mm)
O.D.: 2.49 in. (63.25 mm)
Thickness: 0.375 in. (9.5 mm)
Part No. 201553
1 of 2 holes
0.177 in. dia. (4.5 mm)
120°apart
on 1.625 in. dia. (41.3 mm)
0.44 in. (11.2 mm) opening
90°cut-out
I.D.: 0.625 in. (15.9 mm)
O.D.: 2.46 in. (63.25 mm)
Thickness: 0.375 in. (9.5 mm)
Part No. 201542
4 holes
each 0.15 in. dia. (3.9 mm)
on 0.94 in. dia. (23.9 mm)
I.D.: 0.53 in. (13.5 mm)
O.D.: 1.29 in. (32.8 mm)
Thickness: 0.312 in. (7.9 mm)
I.D.: 0.53 in. (13.5 mm)
O.D.: 1.29 in. (32.8 mm)
Thickness: 0.312 in. (7.9 mm)
1 of 2 holes
0.15 in. dia. (3.9 mm)
120°apart
on 0.94 in. dia. (23.9 mm)
90°cut-out
Part No. 251416
1.1 in.
Ref.
Part No. 251298-1
0.75 in.
Ref.
0.80 in.
Ref.
0.52 in.
Ref.
0.30 in. max.
Aluminum Plate
(bonded to magnet)
Part No. 401032
I.D.: 0.532 in. (13.5 mm)
O.D.: 0.685 in. (17.4 mm)
Thickness: 0.312 in. (7.9 mm)
Max Length: 60 in. (1535 mm)
Part No. 400533
I.D.: 0.53 in. (13.5 mm)
O.D.: 1.0 in. (25.4 mm)
Thickness: 0.312 in. (7.9 mm)
Max. Length: 120 in. (3050 mm)

12
3. Grounding
Figure 3-1
Grounding
Signals Return(s)
Power Return
Frame
Bracket Cover
Cable Shield (no connection)
Head Assembly Grounding Diagram
Signals Return(s)
Power Return
Frame
+Vcc
-Vee
Control Module
(AOM, DIB, Counter Card or other)
(internal to
head enclosure)
Connector
(10 pins)
Ground connection between bracket
and outer cover made by threads
Transducer Rod
(3/8 in. stainless steel)
Machine Ground
Flange
(electrically isolated from threads)
Power Return
Shield Ground
(non current carrying) AC Line
Bracket
Power Supply
Driver/Amplifier
Module
Option Module

13
4. Digital System Configurations
The typical digital system configurations are shown in Figures 4-1, 4-2, and 4-3. Figure 4-1 is a “full” digital sys-
tem. A full digital system includes a Temposonics II LDT with an integrated Digital Personality Module (DPM) and
a Digital Counter Card and supplies either a Binary Coded Decimal (BCD) or Natural Binary output. When
ordered as a scaled system, the components are matched and factory calibrated and will provide an exact, discrete
resolution.
Figures 4-2 and 4-3 illustrate other system configurations which use the output from either the Digital Personality
Module (DPM) or the RS422 Personality Module (RPM) as direct input into a control system. The DPM provides a
pulse duration output and the RPM provides an RS422 interface.
Figure 4-1
Digital System Configuration with DPM, LDT and Digital Counter Card
Figure 4-2
Temposonics II Digital System Configuration
with RS422 Personality Module
Belden YR8105 or equivalent (5 pair)
Power Supply Requirements
• ±12 to ±15Vdc @ 140mA (bipolar)
RS422 Personality Module
User's
Control
System
1µs
RPM
Belden YR8105 or equivalent (5 pair)
Power Supply Requirements
• ±12 to ±15Vdc
@ 150mA (bipolar)
• + 5Vdc
@ 1.2A req. for Counter Card
Digital Personality Module
0
Pulse Duration Output
0
TTL Level
Natural Binary or BCD Output
+5Vdc
Digital
Counter
Card
TTL Level
DPM

14
Figure 4-3
Half Digital System Configuration
with an LDT and a DPM
4.1 Specifications/Digital System Components (Temposonics II with TCS Counter Card)
Parameter Specification
Digital Counter Card
Power Requirements
Voltage: +5 Vdc
Current: 800 mA
Output TTL Compatible, nominal 0 & 5 Vdc, parallel, true high.
Source Current: 0.8 A
Sink Current: 16 mA
(up to 18 bits natural binary, 4 1/4 digit BCD; up to 22 bits binary
and 6 digit BCD can be achieved with a second counter card)
Mounting Distance 300 ft. maximum from Digital Personality Module (DPM)
Digital Personality Module
Recirculations Selectable from 1 to 127
Interrogation Internal
External (1 to 4µs pulse)
Power Requirements
Voltage: ± 15 Vdc
Current: 50 mA
Temperature Requirements
Storage: - 40°F to 180°F (- 40°C to 83°C)
Operating: - 40°F to 180°F (- 40°C to 83°C)
RS422 Personality Module
Interrogation External
Power Requirements
Voltage: ± 15 Vdc
Current: 40 mA
Temperature Requirements
Storage: - 40°F to 180°F (- 40°C to 83°C)
Operating: - 40°F to 180°F (- 40°C to 83°C)
Temposonics II Power Supply
Power Supply Requirements ±15 Vdc at 175 mA maximum, 25 mA minimum
[current draw varies with magnet position, maximum draw occurs
when the magnet is 2 inches (50.8 mm) from the flange and the
minimum update time is being utilized]
Power Supply Requirements
• ±12 to ±15Vdc @ 140mA (bipolar)
Digital Personality Module
User's
Control
System
Pulse Width Output
Belden YR8105
or equivalent (5 pair)
DPM

15
4.2 Digital Personality Module (DPM)
The Digital Personality Module (DPM) replaces the functions provided by the digital interface box. The
DPM, which is roughly the size of a US postage stamp, is installed directly into the transducer head and
provides electronics for pulse shaping, digital recirculations, auto interrogation, and cable interfacing.
Figure 4-4
Excitation Pulse
The waveguide driver board detects a logic level excitation pulse from the DPM. If the device is external-
ly interrogated, an RS422 excitation pulse is fed from an external control system.
The Temposonics linear displacement measurement systems are available with either synchronous or
asynchronous options. These options are available by the configuration of three miniature rotary switches
(SW1, SW2 and SW3).
4.2.1 Synchronous (External Interrogating) Mode
In synchronous operation, an interrogation pulse is supplied to the linear displacement transducer
from an external counter module. After supplying the pulse, the counter module waits until the
recirculation electronics return a termination pulse, and then ends the cycle. The time between
the interrogation and termination pulses is proportional to the distance between the transducer
head assembly and the movable magnet.
In this synchronous mode, SW1 and SW2 are set to the hexadecimal value of the desired number
of recirculations plus 80 (i.e. 81 to FF hex or 129 to 255). SW1 is the least significant digit and
SW2 is the most significant digit. Permissible settings are 81 to FF corresponding to 1 to 127 recir-
culations.
SW3 is ignored in this mode.
Pulse Duration Output
TTL Level
0 V
0 V
RS422 Waveguide
Driver Board
Digital
Personality
Module
Inside Temposonics LDT Head
Excitation Pulse
(IF externally interrogated) Return Pulse
1 µs, nominal
TTL Level
Displacement
NOTE:
Call MTS Sensors Division when replac-
ing a Digital Interface Box with an inte-
grated Digital Personality Module (DPM)

16
Figure 4-5
Timing for Two Circulations
4.2.2 Asynchronous (Internal Interrogating) Mode
In asynchronous operation the transducer interrogates itself. The DPM uses a fixed interrogation
frequency. Switches SW1 and SW2, located on the DPM board, are set to the hexadecimal value
of the desired number of recirculations. Permissible settings are 01 to 7F corresponding to 1 to
127 recirculations.
The update rate in this mode is determined by the following formula:
Refer to the Addendum in the back of this manual for DPM programming procedures.
4.2.3 Operation During Loss of Signal
It is the responsibility of the Digital Counter Card to detect a loss of signal in the system (such as
when the magnet is removed from the rod). The DPM supports this mode by supporting a restart
mode if the Digital Counter Card negates its interrogation cycle before the end of a data acquisi-
tion cycle.
U = (N + 1) * (SW3 + 1) * .2 ms
Where:
U = Update rate in ms
N = # of recirculations selected on SW1 and SW2 (1 to 127)
SW3 = Setting of SW3 (0 to 15)
DPM Output
+Gate
-Gate
ExternalInterrogationTiming
User Defined
UpdateTime

17
Figure 4-6
RS422 Personality Module (RPM)
4.3 RS422 Personality Module (RPM)
The RS422 Personality Module (RPM) is an alternate integrated circuit module. The RPM is also the size of
a US postage stamp and is installed directly into the transducer head to provide the circuitry required to
produce an RS422 start/stop output. This signal is then transmitted to a digital counter card or various
other devices. The RPM must be interrogated by an external source.
The surface mount components of the RPM reduce moment of inertia and enhance shock and vibration
resistance of the module. The simplicity of design makes the module rugged and reliable.
Figure 4-7
The RPM Start/Stop Signal
Waveguide
Driver Board
RS422
Personality
Module
Inside Temposonics LDT Head
Excitation Pulse
(IF externally interrogated) Return Pulse
1 µs, nominal
Interrogation Pluse
TTL Level
0 V
0 V
RS422
1 µs pulse width
TTL Level
Displacement