Руководство по эксплуатации Absolute Shaft Encoders (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 TRANSFER SEQUENCE Block diagram of an absolute shaft encoder Basics of Absolute Encoders ACURO Synchronous-Serial Interface (SSI) In many cases, absolute shaft encoders are The major differences between the concept subject to severe mechanical stresses and of synchronous-serial data transfer for to electrical and magnetic fields that conta- absolute shaft encoders described here minate the site. and parallel and asynchronous serial forms Therefore, special design measures are of data transfer are: needed to combat dirt, dust and liquids in • less electronic components industrial environments.

• less cabling for data transfer Our absolute shaft encoders are of state-of- • the same interface hardware, regardless the-art rugged mechanical construction, of the absolute shaft encoder’s reso- and the electronic components are very lution (word length) compact. • electrical insulation of the shaft encoder A main consideration for immunity to inter- from the control system by optocouplers ference is the data transfer from the shaft • open-circuit monitoring by constant encoder to the control system. The control current system must be able to read the readings • data transfer rates up to 1.5 megabits per from the shaft encoder without errors.

second (depending on the length of line) Under no circumstances should undefined • ring-register operating possible. data be transmitted, for example at the changeover point. For correct transfer of the data a defined As soon as a clock pulse brush is applied to number of pulses (clock pulse brush) must the clock input again, the instantaneous be applied to the clock input of the absolute angular data is recorded. shaft encoder. Next, a pause T must be The first shift of the clock signal from high to P observed.

As long as no clock signal is low x actuates the shaft encoder’s internal applied to the shaft encoder, its internal retriggerable mono-stable element, whose parallel/serial shift register remains storage time tm must be greater than the switched to parallel. The data change con- clock signal’s period T. tinuously, corresponding to the current The output of the monostable element con- position of the shaft encoder’s shaft. trols the parallel/serial register via terminal P/S (parallel/serial). 70 KHz ... 1,5 MHz Doc No: EP0002 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. Basics of Absolute Encoders ACURO Synchronous-Serial Interface (SSI) T = clock pulse period The number of clock pulses necessary for t = storage time of monostable element data transfer is independent of the reso- m t ranging from 10 µs to 30 µs lution of the absolute shaft encoder. m t = 100 ns v The clock signal can be interrupted at any point, or continued in ring-register mode for repeated polling.

With the first shift of the clock signal from A further transfer of data cannot be started low to high y the most significant bit (MSB) until the data line switches to high { again. of the angular data is applied to the shaft If the clock pulse sequence is not interrup- encoder’s serial output. ted at point z, the ring-register mode is With each succeeding rising edge, the next activated automatically. This means that less significant bit is shifted to the data out- the data stored at the first clock pulse tran- put. sition x are returned to the serial input S i After transmission of the least significant via the terminal S .

As long as the clock O bit (LSB) the Alarm bit or other special bits pulse is not interrupted at z, the data can are transferred, depending on configura- be read out as often as wanted (multiple tion. Then the data line switches to low z transfer). until the time t has passed. m Doc No: EP0002 Rev: 001 Impulse Automation Limited United Kingdom Company Registration 665193 Page 2015-03-10 2

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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. RECOMMENDED DATA TRANSMISSION RATE Basics of Absolute Encoders ACURO Synchronous-Serial Interface (SSI) Input circuit Optocoupler Clock Clock Output circuit Driver to EIA 422 A Data Data The maximum data transmission rate depends on the length of cable: Cable length Baud rate Doc No: EP0002 Rev: 001 Impulse Automation Limited United Kingdom Company Registration 665193 Page 2015-03-10 3

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