BEI Sensors THK5 - Manual (Page 3)

POSI+ CANOPEN USER MANUAL
Version 1.02 Page 3
BEI IDEACOD SAS
Espace Européen de l’Entreprise
9, rue de Copenhague
B.P. 70044 Schiltigheim
F 67013 Strasbourg Cedex
Tél : +33 (0)3 88 20 80 80
Fax : +33 (0)3 88 20 87 87
Mail : [email protected]
Web : www.bei-ideacod.com
1. Introduction
This manual describes the implementing and configuration of an absolute rotary encoder with
CANopen interface. The device fullfills the requirements of a CANopen device regarding the
device specification DS406 of the CANopen user group.
1.1 Absolute rotary encoder
The basic principle of an absolute rotary encoder is the optical sampling of a transparent code
disc which is fixed with the driving shaft.
The absolute rotary encoder has a maximum resolution of 8192 steps per revolution (13 Bit). The
Multi-Turn version can detect up to 65536 revolutions (16Bit). Therefore the largest resulting
resolution is 29 Bit = 2
29 = 536.870.912 steps. The standard Single-Turn version has 13 Bit, the
standard Multi-Turn version 29 Bit.
Open functions. The following modes can be programmed and enabled or disabled:
-
RTR Message (Polled mode)
-
Cyclic Mode
-
Sync Mode
The protocol supports the programming of the following additional functions:
-
Code sequence (Complement)
-
Resolution per revolution
-
Total revolutions
-
Preset value
-
Two limit switches
-
Baudrate
-
Node number
The general use of absolute rotary encoders with CAN-Bus interface using the CAN Open
protocol is guaranteed.
1.2 CANopen technology
CAN stands for Controller Area Network and was developed by the company Bosch for
applications within the automobile area. In the meantime CAN has become increasingly used for
industrial applications. CAN is a multi-masterable system, i.e. all users can access the bus at any
time as long as it is free. CAN doesn’t operate with addresses but with message identifiers. Access
to the bus is performed according to the CSMA/CA principle (carrier sense multiple access with
collision avoidance), i.e. each user listens if the bus is free, and if so, is allowed to send messages.
If two users attempt to access the bus simultaneously, the one with the highest priority (lowest
identifier) receives the permission to send. Users with lower priority interrupt their data transfer and
will access the bus when it is free again. Messages can be received by every participant.
Controlled by an acceptance filter the participant accepts only messages that are intended for
it.