BECKHOFF KL3351 User Manual

KL3351

1-Channel Resistor Bridge Input Terminal
Configuration Instructions

Version 2.2
2006-10-23

Contents

Contents

1. Foreword 3

Notes on the documentation 3
Safety Instructions 4

2. Technical data 5

3. Description of functions 6

4. Terminal configuration 7

5. Register description 8

General register description 8
Terminal-specific register description 11
Register communication KL3351 12

6. Annex 15

Mapping in the bus coupler 15
Table of the register 17

7. Support and Service 18

Beckhoff Headquarters 18

2 KL3351

Foreword

Foreword

Notes on the documentation

This description is only intended for the use of trained specialists in control and automation engineering
who are familiar with the applicable national standards. It is essential that the following notes and
explanations are followed when installing and commissioning these components.

Liability Conditions

The responsible staff must ensure that the application or use of the products described satisfy all the
requirements for safety, including all the relevant laws, regulations, guidelines and standards.

The documentation has been prepared with care. The products described are, however, constantly under
development. For that reason the documentation is not in every case checked for consistency with
performance data, standards or other characteristics. None of the statements of this manual represents a
guarantee (Garantie) in the meaning of § 443 BGB of the German Civil Code or a statement about the
contractually expected fitness for a particular purpose in the meaning of § 434 par. 1 sentence 1 BGB. In
the event that it contains technical or editorial errors, we retain the right to make alterations at any time
and without warning. No claims for the modification of products that have already been supplied may be
made on the basis of the data, diagrams and descriptions in this documentation.

Delivery conditions

In addition, the general delivery conditions of the company Beckhoff Automation GmbH apply.

Copyright

©

This documentation is copyrighted. Any reproduction or third party use of this publication, whether in

whole or in part, without the written permission of Beckhoff Automation GmbH, is forbidden.

KL3351 3

Foreword

i

Safety Instructions

State at Delivery

All the components are supplied in particular hardware and software configurations appropriate for the
application. Modifications to hardware or software configurations other than those described in the
documentation are not permitted, and nullify the liability of Beckhoff Automation GmbH.

Description of safety symbols

The following safety symbols are used in this documentation. They are intended to alert the reader to the
associated safety instructions..

This symbol is intended to highlight risks for the life or health of personnel.

Danger

This symbol is intended to highlight risks for equipment, materials or the

Attention

environment.
This symbol indicates information that contributes to better understanding.

Note

4 KL3351

The power supply Uv can be obtained from the terminal

+Uref

+Uref

- Uref

- Uref

Technical data

13

14

RUN - LED1

Error - LED1

A
B

C
D

U

r

U

D

RUN - LED2
Error - LED2

Technical data

+U

V

+ U

- U

-U =0V

V

Shield

D

D

1

2

3

4

5

-U

r

-U

D

6

-U

V

+ V

U

7

S

S

8

+ U

- U

+U =5V

Shield

Top View Contacts Contact Assembly

Technical data KL3351

Number of inputs

Power supply

Signal voltage UD

Signal voltage U

Internal resistance

Power supply UV

Resolution

Conversion time

Measuring error (total measuring range)

Filter

Electrical isolation

Current consumption from K-Bus

Bit width in the process image

Operating temperature

Storage temperature

Relative humidity

Vibration/shock resistance

EMC resistance Burst / ESD

Installation position

Type of protection

ref

ref

V

+U

- U

- U

D

+U

D

- U

- U

D

V

D

V

+U

V

or can be feed in external.
The terminal supplies 5 V.
The maximum input voltage Uref is limited to 10 V.

2, for one resistor bridge
via the K-Bus

-16 mV ... +16 mV, configurable

-10 V ... +10 V, configurable

ref

> 200 kΩ (U
5 V, 20 mA
16 bits
< 250 ms. Configurable
< ± 0.1% (of the upper range value)
50 Hz, configurable
500 Vrms (K-Bus / signal voltage )
65 mA typ.
I: 2 x 16 bits data (2 x 8 bits control/status)
0°C ... +55°C

-25°C ... +85°C
95%, no condensation
conforms to IEC 68-2-6 / IEC 68-2-27
conforms to EN 50082 (ESD, Burst) / EN 50081
any
IP20

ref

), > 1 MΩ (UD)

KL3351 5

Description of functions

Description of functions

The KL3351 analogue input terminal permits direct connection of a

resistance bridge. The bridge voltage, UD, and the supply voltage, U

ref

, to
the bridge are digitised with 16 bits resolution, and are transmitted over an
electrically isolated channel to the supervising automation system. The
input channels are available in the form of two 16 bit values for further
processing. The resulting measurement can be calculated from the
formula: measurement = UD / U

. Precise acquisition of the supply voltage

ref

along with the bridge voltage compensates for long-term and temperature
drift.

Output of the measurement

The bridge voltage between +UD and –UD is output with a resolution of
500 nV/digit, so that 10 mV corresponds to an output value of 20000 in the
data bytes D0 and D1 of channel 1.

The supply voltage for the bridge is output with a resolution of 500 µV/digit,
so that 10 V corresponds to the output value 20000 in the data bytes D0
and D1 of channel 2.

The resolution can be adjusted by means of gain register R38.

Example

A load cell was connected to the KL3351 in an experimental test bed.
The load cell was fed with the terminal’s 5 V supply voltage (UV), while the

reference voltage (U

) and the bridge voltage were captured with the U

ref

ref

and UD channels respectively.
Technical data for the load cell:
5 kg = 2 mV/V
The weight is calculated as follows:
Weight = UD / U

* 5/0.002 [kg]

ref

Bridge supply

If the internal voltage supply is overloaded (I_load > 20 mA), it is
recommended that a KL9505 or a KL9510 be used.

LED display

The four LEDs indicate the operating state of the associated terminal
channels.

Green LEDs: RUN
On: normal operation
Off: Watchdog-timer overflow has occurred. If no process data is

transmitted to the bus coupler for 100 ms, the green LEDs go out.
Red LEDs: ERROR
Error LED1: outside the acceptable range for the signal voltage (UD), or

broken wire
Error LED2: outside the acceptable range for the reference voltage (U

)

ref

6 KL3351