User Manual

POSI+ CANOPEN USER MANUAL
Version 1.02 Page 3
BEI IDEACOD SAS
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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 specificati on DS406 of the CA Nopen 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 functi ons. 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 follo wing additional functions:
- Code sequence (Complem ent)
- Resolution per rev o lution
- 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 withi n th e au tomobil e are a. In the meanti m e CAN has becom e i ncreasi ngl y 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 i s free. CA N doesn’t opera te with addresses bu t with mess age i dentifiers. Access
to the bus is performed according to the CSMA/CA principle (carrier sense multiple access with
collision av oidance), i.e. each us er listens i f the bus is free, a nd if so, i s allowed to send messages .
If two users attempt to access the bus simultaneously, the one with the highest priority (lowest
identi fier) receiv es the permi ssi on to send. Us ers with l ower pri ority interrupt their data tr ansfer 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.