Basics of Absolute Encoders with Profibus (EN)

email: sales@impulseautomation.co.uk web: www.impulseautomation.co.uk Information shown in these data sheets are for guidance purposes only, no liability is accepted for any errors or omissions. The designer or user is solely responsible for the safe and proper use of these parts, assemblies or equipment described. GENERAL INFORMATION INTRODUCTION FIELD OF APPLICATION BASIC FUNCTIONS OF THE PROFIBUS-DP Basics of Absolute Encoders ACURO Profibus-DP The basic functions of the PROFIBUS DP are here only described in extracts. For additional information, please refer to the standards on PROFIBUS DP, i.e. DIN 19245- 3 and EN 50170 respectively.

The AC 58 is an absolute shaft encoder PROFIBUS-DP permits the communication (encoder, angle encoder). The version of devices produced by different manufac- described in this manual sends its current turers without any particular adaptations of position to another station via the transmis- the interfaces. sion medium "PROFIBUS DP" (physically: PROFIBUS DP is a special standard version screened and twisted pair line). The AC 58 for a quick data exchange within the field supports all class 1 and 2 functions listed in level which has been optimised in terms of the encoder profile. speed and low connection costs.

Central control systems like, for example SPC/ PC PROFIBUS-DP is manufacturer indepen- communicate via a quick, serial connection dent, open field bus standard for a variety of with local field devices like drives, valves, applications in the field of production, pro- or encoders. The data exchange between cess and building services automation. The these devices is predominantly cyclical. requirements of openness and indepen- The communication functions required for dence from the manufacturer are stipulated this exchange are determined by the basic in the European standard EN 50 170. functions of the PROFIBUS DP according to the EN 50 170 European standard.

In systems, where the position of a drive or The AC 58 can resolve, for instance, positio- of any other part of a machine has to be ning tasks by sending the checkback signal recorded and signalled to the control concerning the present drive position via system, the AC 58 can assume this function. the PROFIBUS DP to the positioning unit. The central control system (master) cycli- Apart from the cyclical user data transfer, cally reads out the input information from the PROFIBUS DP version also disposes of the slaves and writes the output information powerful functions for diagnosis and initial to the slaves. For this purpose, the bus operation procedures.

The data traffic is cycle time has to be shorter than the controlled by watchdog functions on both program cycle time of the central SPC, the slave and the master side. The following which amounts to approx. 10 ms for various table summarises the basic functions of the applications. PROFIBUS DP. Doc No: EP0003 Rev: 001 Impulse Automation Limited United Kingdom Company Registration 665193 Page 2015-03-10 1

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Information shown in these data sheets are for guidance purposes only, no liability is accepted for any errors or omissions. The designer or user is solely responsible for the safe and proper use of these parts, assemblies or equipment described. ESSENTIAL FEATURES/ SPEED Basics of Absolute Encoders ACURO Profibus-DP Transmission technology: • RS-485 twisted pair line • Baud rates ranging from 9.6 kBit/s up to 12 MBit/s Bus access: • Token passing procedure between the masters and master-slave procedures for slaves • Monomaster or multimaster systems possible • master and slave devices, max. of 126 stations at a single bus Communication:

• Point-to-point (user data communication) or multicast (control commands) • cyclical master-slave user data communication and acyclical master-master data transfer Operating state: • Operate:cyclical transfer of input and output data • Clear: The input data are read, the output data remain in the safe status • Stop: only master-master data transfer is possible Synchronisation: • Control commands enable a synchronisation of the input and output data • Sync mode: Output data are being synchronised Functionality: • Cyclical user data transfer between DP master and DP slave(s) • Single DP slaves are dynamically activated or deactivated • Control of the DP slave's configuration.

Powerful diagnostic functions, 3 stepped diagnostic message levels. • Synchronisation of in- and/ or output • Address assignment for the DP slaves via the bus • Configuration of the DP masters (DPM1) via the bus • Maximum of 246 byte input and output data per DP slave possible Protection functions: • All messages are transferred with a hamming distance of HD=4 • Response control at the DP slaves • Access protection of the DP slaves' input/ output • Monitoring of the user data communication with adjustable control timer at the master Device types: • DP master class 2 (DPM2), e.g. programming/ project planning devices • DP master class 1 (DPM1), e.g.

central automation devices like SPC, PC • DP slave e. g. devices with binary or analogue input/ output, drives, valves The PROFIBUS DP only requires approx. Diagnostic function: 1 ms at a speed of 12 MBit/s in order to The comprehensive diagnostic functions of transfer 512 Bit input and 512 Bit output data PROFIBUS DP allow a quick localisation of by means of 32 stations. the errors. The diagnostic messages are The following diagram shows the usual transferred by means of the bus and are PROFIBUS DP transfer time interval in rela- assembled at the master. They are subdivi- tion to the number of stations as well as the ded in three levels: transmission speed.

The high speed can be above all explained by the fact that the input and output data within a message cycle are transferred by using the layer 2 SRD service (Send and Receive Data Service). Doc No: EP0003 Rev: 001 Impulse Automation Limited United Kingdom Company Registration 665193 Page 2015-03-10 2 Transmission technology: • RS-485 twisted pair line • Baud rates ranging from 9.6 kBit/s up to 12 MBit/s Bus access: • Token passing procedure between the masters and master-slave procedures for slaves • Monomaster or multimaster systems possible • master and slave devices, max. of 126 stations at a single bus Communication:

• Point-to-point (user data communication) or multicast (control commands) • cyclical master-slave user data communication and acyclical master-master data transfer Operating state: • Operate:cyclical transfer of input and output data • Clear: The input data are read, the output data remain in the safe status • Stop: only master-master data transfer is possible Synchronisation: • Control commands enable a synchronisation of the input and output data • Sync mode: Output data are being synchronised Functionality: • Cyclical user data transfer between DP master and DP slave(s) • Single DP slaves are dynamically activated or deactivated • Control of the DP slave's configuration.

Powerful diagnostic functions, 3 stepped diagnostic message levels. • Synchronisation of in- and/ or output • Address assignment for the DP slaves via the bus • Configuration of the DP masters (DPM1) via the bus • Maximum of 246 byte input and output data per DP slave possible Protection functions: • All messages are transferred with a hamming distance of HD=4 • Response control at the DP slaves • Access protection of the DP slaves' input/ output • Monitoring of the user data communication with adjustable control timer at the master Device types: • DP master class 2 (DPM2), e.g. programming/ project planning devices • DP master class 1 (DPM1), e.g.

central automation devices like SPC, PC • DP slave e. g. devices with binary or analogue input/ output, drives, valves

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Information shown in these data sheets are for guidance purposes only, no liability is accepted for any errors or omissions. The designer or user is solely responsible for the safe and proper use of these parts, assemblies or equipment described. BASIC FEATURES/SPEED CONFIGURATION OF THE SYSTEM AND DEVICE TYPES Basics of Absolute Encoders ACURO Profibus-DP Station-related diagnosis Channel related diagnosis Messages on the general readiness for ser- The error cause in relation to a single input/ vice of a station, like for example, overtem- output bit (channel) is indicated here, like perature or undervoltage. for example, a short-circuit at output line 7.

Module-related diagnosis Theses messages indicate that a diagnosis within a certain I/O part (e.g. 8 Bit output module) of a station is in hand. Bus cycle time of a PROFIBUS DP monomaster system Boundary conditions: Each slave has 2 byte input and 2 yte output data; the minimum slave interval time amounts to 200 microseconds; TSDI = 37 Bit times, TSDR = 11 Bit times By means of PROFIBUS DP, mono- and DP master class 2 (DPM2) mulitmaster systems can be realised. For Programming, configuration devices, and this reason, a high level of flexibility in terms operator panels belong to this category. of the system configuration can be achie- They are used for the initial operation ved.

A maximum of 126 devices (master or procedures in order to establish the confi- slaves) may be connected to a bus. The guration of the DP system, or to operate the definitions for the system configuration plants in the course of operation. contain the number of stations, the assign- ment of the station address to the I/O DP slave addresses, the data consistency of the I/O A DP slave is a peripheral I/O rack (I/O, dri- data, the format of the diagnostic messages ves, HMI, valves) that reads the input and the bus parameters used. Each information and sends output information to PROFIBUS DP system consists of different the peripheral equipment. Devices which device types.

There are three device types to provide only input or only output informa- be distinguished: tion might also be used. The amount of input and output information DP master class 1 (DPM1) is device specific and must not exceed 246 These devices are central control systems byte for the input and 246 byte for the output exchanging information with the local data. stations (DP slaves) during a fixed message cycle. Typical devices of this kind are stored-program controllers (SPC), PC or VME systems. Doc No: EP0003 Rev: 001 Impulse Automation Limited United Kingdom Company Registration 665193 Page 2015-03-10 3

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Information shown in these data sheets are for guidance purposes only, no liability is accepted for any errors or omissions. The designer or user is solely responsible for the safe and proper use of these parts, assemblies or equipment described. Basics of Absolute Encoders ACURO Profibus-DP DP-Master (Class 1) decentral inputs and outputs PROFIBUS DP monomaster system In the case of monomaster bus systems, In the multimaster mode, several masters there is only one master active at bus are linked to a single bus. They either form during the on-line phase of the bus system.

independent subsystems consisting of one The above diagram shows the system con- DPM1 and its corresponding DP slaves figuration of a monomaster system. each, or additional configuration and The SPC based control system is the diagnostic devices (see diagram below). central control element. By means of the The I/O maps of the DP slaves can be read transmission medium, the DP slaves are by all DP masters, but only one DP master, locally linked to the SPC control system. By the one which has been assigned DPM1 using this system configuration, the during project planning, is able to write the shortest bus cycle time can be obtained. output information.

Multimaster systems attain a medium bus cycle time. decentral inputs and outputs decentral inputs and outputs several masters can read the data of the DP slaves PROFIBUS-DP Multi-Master System Doc No: EP0003 Rev: 001 Impulse Automation Limited United Kingdom Company Registration 665193 Page 2015-03-10 4

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