Netzer AqBiSS Electric Encoders

Netzer AqBiSS Electric Encoders AqBiSS universal fully digital interface Application Note (AN-101-00) Copyright 2003 Netzer Precision Motion Sensors Ltd. Teradion Industrial Park, POB 1359 D.N. Misgav, Israel 20179 Tel: +972 (4) 999 0420 Fax: +972 (4) 999 0432 E-Mail: info@netzerprecision.com Changes are periodically made to the information contained in this document. No part of this guide may be reproduced in any form, without permission in writing from Netzer. Source for all drawings: STA - http://www.biss-interface.com/)

CONTENTS Contents 2 Figures 3 Tables 3 1. AqBiSS AqBI and BiSS Interface for Electric Encoders 4 1.1. Encoder Block Diagram 5 2. Using AqBiSS with Absolute NetzerAqBiSS Electric Encoders 6 2.1. Reading the Absolute Position 6 3. Using AqBiSS with incremental NetzerAqBiSS Electric Encoders 10 4. Working with Netzer AqBiSS Electric Encoders 11 4.1. Incremental AqBiSS Electric Encoders 11 4.2. Absolute Electric Encoders 12 4.3. Interface to Controller (Closed Loop) 13 4.4. Evaluation Kit (Open Loop) 14 5. Disclaimer 17 6. Appendix A: Detailed Description of the AqBiSS Interface 18 6.1. AqBI Channel 18 6.2. BiSS Channel 19 6.3. AqBiSS Electrical Interface 22 6.4. BiSS Master Controller Requirements 24 6.5. Memory Structure 25 AN101_AqBiSSInterface_01.doc Copyright 2003 Netzer Precision Motion Sensors Ltd. Page 2 of 2

FIGURES FIGURE 1-1 AqBiSS signals (source for all drawings: STA - http://www.biss-interface.com/)... 4 FIGURE 1-2 Netzer AqBiSS Electric Encoder block diagram... 5 FIGURE 2-3 Coarse and fine electrical angles and mechanical angle... 7 FIGURE 4-4 Absolute encoder AqB + BiSS connection... 14 FIGURE 4-5 Evaluation kit connection... 15 FIGURE 4-6 Encoder evaluation software... 15 FIGURE 4-7 Netzer AqBiSS Electric Encoder Evaluation Kit... 16 FIGURE 6-8 AqBI waveform... 18 FIGURE 6-9 Point-to-point BiSS application (source: STA - http://www.biss-interface.com/).. 19 FIGURE 6-10 Sensor mode read cycle (* includes error checking)... 21 FIGURE 6-11 Signals in register mode address sequence... 21 FIGURE 6-12 Signals in register mode read access... 21 FIGURE 6-13 Signals in register mode write access... 21 FIGURE 6-14 AqBiSS interface circuit... 23 FIGURE 6-15 Encoder EEPROM addresses... 25 TABLES TABLE 4-1 AqBI interface for Incremental AqBiSS Electric Encoder... 11 TABLE 4-2 BiSS only interface for AqBiSS Electric Encoder... 12 TABLE 4-3 AqB + BiSS interface for Absolute AqBiSS Electric Encoder... 13 TABLE 6-4 AqBiSS Pin Assignment... 24 AN101_AqBiSSInterface_01.doc Copyright 2003 Netzer Precision Motion Sensors Ltd. Page 3 of 3

- AQBISS AQBI AND BISS INTERFACE FOR ELECTRIC ENCODERS - 1. AqBiSS AqBI and BiSS Interface for Electric Encoders AqBiSS is a new, fully-digital interface for absolute and incremental encoders. It combines an A quad B incremental interface with the open-standard, high-speed Bidirectional Serial Sensor (BiSS) absolute interface. AqBiSS is a fast and robust interface suitable for real time communication. This document provides a detailed description of the AqBiSS interface and how to use it with NetzerAqBiSS Electric Encoders. A B i AqB,I Incremental Position MA SL BiSS Absolute Position Incremental Position FIGURE 1-1 AqBiSS signals (source for all drawings: STA - http://www.bissinterface.com/) AN101_AqBiSSInterface_01.doc Copyright 2003 Netzer Precision Motion Sensors Ltd. Page 4 of 4

- AQBISS AQBI AND BISS INTERFACE FOR ELECTRIC ENCODERS - 1.1. Encoder Block Diagram FIGURE 1-2 is a block diagram of a Netzer AqBiSS Electric Encoder (NE 2 ). AqBiSS FIGURE 1-2 Netzer AqBiSS Electric Encoder block diagram The NetzerAqBiSS Electric Encoder contains a fixed transmitter and receiver and a revolving rotor that is made of dielectric material, and is attached to the motor shaft. The transmitter contains two excitation plates (Tx) The Fine and Coarse. The receiver consists of a receiving plate (Rx). The amplifier (A1) amplifies the received signal that its phase is a function of the rotor angle. The detector (A2) splits this signal. The split signals feed two 4 khz low-pass filters (A3 & A4) resulting in a quadrant pair of sine and cosine of the rotor angle. The sine-cosine pair feeds the Sine-to-Digital (S/D) converter (A5). The S/D converts the sine-cosine pair into digital position data. The digital data is available to the user in two formats. AqB and Index format and a digital word format that is accessed via the BiSS channel. The Serial EEPROM (A8) stores encoder parameters. It is accessed by the user through the BiSS channel. The microcontroller (A9) has two functions: 1. It generates a pair of high frequency (~55 khz) excitation signals that are shifted by 90º one relative to the other. 2. It controls via the demultiplexer (A10) which plate is excited the Fine or Coarse plate. AN101_AqBiSSInterface_01.doc Copyright 2003 Netzer Precision Motion Sensors Ltd. Page 5 of 5

- USING AQBISS WITH ABSOLUTE NETZERAQBISS ELECTRIC ENCODERS - 2. Using AqBiSS with Absolute NetzerAqBiSS Electric Encoders 2.1. Reading the Absolute Position The absolute position is read once, at the start of motion. After that the position is tracked by reading incremental changes. There are two ways to do this: 1. Use the BiSS channel for both the initial reading and for the incremental readings. For this configuration, the controller s BiSS interface must be high-speed, for example, a dedicated BiSS master chip. This configuration uses only four communication wires and is very robust. 2. Use the BiSS channel for the initial reading and then use the AqB for the incremental readings. In this configuration, a slow BiSS interface is adequate, for example, the Netzer s AqBiSS-to-RS-232 Converter. Upon initialization, the controller reads the position of the course channel and fine channel (via the BiSS) and calculates the absolute position. Afterwards, every sampling interval, the controller reads only the fine channel and updates the actual position. 2.1.1. Finding the Initial Absolute Position In Netzer Precision Electric Encoders, more than one pole is used, meaning there is more than one electrical cycle per revolution. Both the mechanical angle and the electrical angle are measured. FIGURE 2-3 is an example of the two angle measurement structures. The inside structure is referred to as the course structure (in this example it has 3 poles). The outside structure is referred to as the fine structure (in this example it has 8 poles). Different mechanical (real) angles and their relative electrical angles are shown. The initial BiSS reading finds the absolute position using the MN algorithm, based on the coarse and fine readings. AN101_AqBiSSInterface_01.doc Copyright 2003 Netzer Precision Motion Sensors Ltd. Page 6 of 6

- USING AQBISS WITH ABSOLUTE NETZERAQBISS ELECTRIC ENCODERS - angle angle angle FIGURE 2-3 Coarse and fine electrical angles and mechanical angle 2.1.2. Using Only the BiSS for Position Reading 2.1.2.1. Initializing Absolute Position Upon start-up/initialization (T n =0), the controller does the following: 1. Switch the encoder to coarse mode by setting the corresponding sin-to-digital converter (A5 in FIGURE 1-2) registers. 2. Read the course channel value. 3. Switch the encoder to fine mode by setting the corresponding sin-to-digital converter (A5 in FIGURE 1-2) registers. 4. Read the fine channel value. 5. Calculate current absolute position and assign to AP0 based on MN algorithm. 6. Add to the calculated position the UZP (user s zero position). 2.1.2.2. Updating Actual Position Incrementally Afterwards, for each sampling interval (n>0): 1. Read fine channel. AN101_AqBiSSInterface_01.doc Copyright 2003 Netzer Precision Motion Sensors Ltd. Page 7 of 7

- USING AQBISS WITH ABSOLUTE NETZERAQBISS ELECTRIC ENCODERS - 2. Calculate the actual position using the following algorithm: AP n =AP (n-1) + (FCP n -FCP (n-1) ) where AP n Actual Position at sampling interval n. FCP n Fine Channel Position reading at interval n. 2.1.2.3. Note: full algorithm is presented in: Application note AN102, AqBiSS Electric Encoder - calculating absolute position Speed Limitations 2.1.2.3.1. Initial Reading Speed Limitations During initial reading of the course and fine channels, the motor should not move more then one half of the fine cycle, which imposes a maximum speed on the encoder as follows: rotary encoders 60 rpm linear encoders (see table in product data sheet) 2.1.2.3.2. Incremental Tracking Speed Limitations Between two tracking readings, the motor should not move more then one half of the fine cycle, which imposes a maximum speed on the encoder as follows: S < MST * N * 2 * 60000 where MST Maximum Sampling Time msec N- number of fine poles S Speed in RPM 2.1.3. Using BiSS Together with AqB for Position Reading 2.1.3.1. Initializing Absolute Position Upon start-up/initialization (T n =0), the controller does the following: 1. Switch the encoder to coarse mode by setting the corresponding sin-to-digital converter (A5 in FIGURE 1-2) registers. 2. Read the course channel value. 3. Switch the encoder to fine mode by setting the corresponding sin-to-digital converter (A5 in FIGURE 1-2) registers. 4. Simultaneously read the fine channel and latch the controller s AqB counter value (C -1 ). 5. Calculate current absolute position and assign to AP0 based on MN algorithm. 6. Set C 0 = AP 0 (C 0 - C -1 ). (This is done to correct for the counter moving during step 5 from C -1 to C 0.) AN101_AqBiSSInterface_01.doc Copyright 2003 Netzer Precision Motion Sensors Ltd. Page 8 of 8

- USING AQBISS WITH ABSOLUTE NETZERAQBISS ELECTRIC ENCODERS - Note: full algorithm is presented in: Application note AN102 AqBiSS Electric Encoder - calculating absolute position 2.1.3.2. Actual Position Incrementally Afterwards, the counter automatically follows the position. 2.1.3.3. Speed Limitations 2.1.3.3.1. Initial Reading Speed Limitations During initial reading of the course and fine channels, the motor should not move more then one half of the fine cycle, which imposes a maximum speed on the encoder as follows: rotary encoders 60 rpm linear encoders (see table in product data sheet) 2.1.3.3.2. Incremental Tracking Speed Limitations Depends on the controller. AN101_AqBiSSInterface_01.doc Copyright 2003 Netzer Precision Motion Sensors Ltd. Page 9 of 9

- USING AQBISS WITH INCREMENTAL NETZERAQBISS ELECTRIC ENCODERS - 3. Using AqBiSS with incremental NetzerAqBiSS Electric Encoders 3.1.1. Using Only the BiSS for Position Reading 3.1.1.1. Initialization Upon start-up/initialization (T n =0), the controller does the following: 1. Read the fine channel value and assign it to AP0. 3.1.1.2. Updating the Actual Position Incrementally Afterwards, for each sampling interval (n>0): 1. Read fine channel. 2. Calculate the actual position using the following algorithm: AP n =AP (n-1) + (FCP n -FCP (n-1) ) where AP n Actual Position at sampling interval n. FCP n Fine Channel Position reading at interval n. Note: full algorithm is presented in: Application note AN102 AqBiSS Electric Encoder - calculating absolute position 3.1.1.2.1. Incremental Tracking Speed Limitations Between two tracking readings, the motor should not move more then one half of the fine cycle, which imposes a maximum speed on the encoder as follows: S < MST * N * 2 * 60000 where MST Maximum Sampling Time msec N- number of fine poles S Speed in RPM 3.1.2. Using AqBI for Position Reading Read the controller s AqBI counter AN101_AqBiSSInterface_01.doc Copyright 2003 Netzer Precision Motion Sensors Ltd. Page 10 of 10

- WORKING WITH NETZER AQBISS ELECTRIC ENCODERS - 4. Working with Netzer AqBiSS Electric Encoders 4.1. Incremental AqBiSS Electric Encoders 4.1.1. Using AqBI Alone Can be used with any motion controller that supports this de facto industry-standard interface. Cabling: Uses total of 8 lines (TABLE 4-1) A+, A- B+, B- I+, I- 5V, GND TABLE 4-1 AqBI interface for Incremental AqBiSS Electric Encoder Pin No Signals Description 1 Vc 5V Power Supply 2 GND Ground (return Power Supply) 3 A+ A positive (AqB), output 4 A- A negative (AqB), output 5 B+ B positive (AqB), output 6 B- B negative (AqB), output 7 I+ Index positive (AqB), output 8 I- Index negative (AqB), output 9 MA+ Master positive (BiSS clock), input 10 MA- Master negative (BiSS clock), input 11 SL+ Slave positive (BiSS data), output 12 SL- Slave negative (BiSS data), output 4.1.2. Using BiSS Alone Motion controller must have native BiSS support or an external high-speed adapter. Cabling: Uses total of 6 lines (TABLE 4-2) AN101_AqBiSSInterface_01.doc Copyright 2003 Netzer Precision Motion Sensors Ltd. Page 11 of 11

- WORKING WITH NETZER AQBISS ELECTRIC ENCODERS - MA+, MA- SL+, SL- 5V, GND TABLE 4-2 BiSS only interface for AqBiSS Electric Encoder Pin No Signals Description 1 Vc 5V Power Supply 2 GND Ground (return Power Supply) 3 A+ A positive (AqB), output 4 A- A negative (AqB), output 5 B+ B positive (AqB), output 6 B- B negative (AqB), output 7 I+ Index positive (AqB), output 8 I- Index negative (AqB), output 9 MA+ Master positive (BiSS clock), input 10 MA- Master negative (BiSS clock), input 11 SL+ Slave positive (BiSS data), output 12 SL- Slave negative (BiSS data), output 4.2. Absolute Electric Encoders 4.2.1. Using BiSS Alone Same requirements as for Incremental Electric Encoder working with BiSS alone (Section 4.1.2). Controller operation is as follows: 1. Upon power up, sample the Coarse channel position. 2. Switch to the Fine channel. 3. Sample the Fine channel position. 4. Calculate the absolute position (MN algorithm). 5. Continue sampling the Fine channel. 4.2.2. Using AqB + BiSS Operation is same as BiSS alone (Section ) except that after the absolute position is calculated, sampling continues via the AqB channel rather than via the BiSS channel. This configuration enables position based triggering. Cabling: Uses total of 10 lines (TABLE 4-2) AN101_AqBiSSInterface_01.doc Copyright 2003 Netzer Precision Motion Sensors Ltd. Page 12 of 12

- WORKING WITH NETZER AQBISS ELECTRIC ENCODERS - BiSS (MA+/-, SL+/-) AqB (A+/-, B+/-) 5V, GND TABLE 4-3 AqB + BiSS interface for Absolute AqBiSS Electric Encoder Pin No Signals Description 1 Vc 5V Power Supply 2 GND Ground (return Power Supply) 3 A+ A positive (AqB), output 4 A- A negative (AqB), output 5 B+ B positive (AqB), output 6 B- B negative (AqB), output 7 I+ Index positive (AqB), output 8 I- Index negative (AqB), output 9 MA+ Master positive (BiSS clock), input 10 MA- Master negative (BiSS clock), input 11 SL+ Slave positive (BiSS data), output 12 SL- Slave negative (BiSS data), output 4.3. Interface to Controller (Closed Loop) To gain access of the absolute positing, BiSS channel interface is required: 4.3.1.1. Controllers with Built-In BiSS Support Controllers with native BiSS support can use either the BiSS channel or the AqB channel for sampling after absolute position calculation. An advantage of using the AqB channel is that it enables position triggering (if necessary). 4.3.1.2. Controllers with RS-232 Channel If the controller does not have a BiSS channel but does have an RS-232 channel, then an external BiSS adapter can be used, such as the Netzer AqBiSS-to-RS-232 converter (FIGURE 4-4). The AqBiSS-to-RS-232 converter provides a BiSS interface with AqBI passthrough. As there is a need to synchronize the controller counter with the data read from the BiSS channel, a latch signal (see Section 2.1.3.1) is sent from the kit to the controller. AN101_AqBiSSInterface_01.doc Copyright 2003 Netzer Precision Motion Sensors Ltd. Page 13 of 13

- WORKING WITH NETZER AQBISS ELECTRIC ENCODERS - Netzer AqBiSS-to- RS-232 Converter Netzer AqBiSS Electric Encoder J2 J3 RS-232 Controller J1 AqBI FIGURE 4-4 Absolute encoder AqB + BiSS connection Need to write a program in the controller that reads the coarse and fine position data, calculates the initial absolute position, and initializes the controller s software position counter. Afterwards it uses the AqB input to track the position. Using it this way enables position triggering based on the controller s hardware position counter 4.3.1.2.1. Converter Power Requirements The AqBiSS-to-RS-232 Converter requires up to 500 mamp to operate with a fully-terminated Netzer AqBiSS Electric Encoder. If the controller cannot provide this power, then it is recommended to use the external power supply provided with the kit. Note: full implantation is presented in: Application note AN103 Using AqBiSS absolute Electric Encoder with ACS-Tech80 SpiiPlus controller 4.4. Evaluation Kit (Open Loop) Netzer provides an AqBiSS Electric Encoder Evaluation Kit for open-loop operation via a personal computer. The kit includes all required hardware, including encoder and cables (FIGURE 4-5). The kit software provides an easy-to-use graphical interface (FIGURE 4-6), with no need for programming. The evaluation kit cannot be used for real-time control. AN101_AqBiSSInterface_01.doc Copyright 2003 Netzer Precision Motion Sensors Ltd. Page 14 of 14

- WORKING WITH NETZER AQBISS ELECTRIC ENCODERS - Netzer AqBiSS Electric Encoder Netzer AqBiSS-to- RS-232 Converter J4 J2 J3 Power Supply PC FIGURE 4-5 Evaluation kit connection FIGURE 4-6 Encoder evaluation software AN101_AqBiSSInterface_01.doc Copyright 2003 Netzer Precision Motion Sensors Ltd. Page 15 of 15

- WORKING WITH NETZER AQBISS ELECTRIC ENCODERS - 4.4.1. Kit Description FIGURE 4-7 Netzer AqBiSS Electric Encoder Evaluation Kit The Netzer AqBiSS Electric Encoder Evaluation Kit (FIGURE 4-7) includes the following: AqBiSS Electric Encoder mounted on a jig with connection cable AqBiSS-to-RS-232 converter (Section 4.3) Converter-to-RS-232 cable External power supply CD with Software and User's Guide Note: full implantation is presented in: AqBiSS Electric Encoder evaluation kits user manual AN101_AqBiSSInterface_01.doc Copyright 2003 Netzer Precision Motion Sensors Ltd. Page 16 of 16

- DISCLAIMER - 5. Disclaimer NETZER PRECISION MOTION SENSORS (Netzer Precision) is not liable for any damages (material, financial, or physical) caused by its products or the failure of the products to perform. These limits of liability shall including, but not limited to: any lost profits, lost savings, lost earnings, loss of programs or other data, business interruption, incidental damages, consequential damages or personal injury. These limitations apply whether damages are sought, or a claim made, under this warranty or as a tort claim (including negligence and strict product liability), or any other claim. These limitations of liability will be effective even if you have advised Netzer Precision of the possibility of any such damages. Netzer Precision makes no other warranties, expressed or implied, including any implied warranties of merchantability or fitness of any product for a particular purpose. Netzer Precision expressly disclaims all warranties not stated in this warranty. Netzer Precision reserves the right to make change to this warranty without notice. AN101_AqBiSSInterface_01.doc Copyright 2003 Netzer Precision Motion Sensors Ltd. Page 17 of 17

- APPENDIX A: DETAILED DESCRIPTION OF THE AQBISS INTERFACE - 6. Appendix A: Detailed Description of the AqBiSS Interface AqBiSS combines a fast incremental A quad B + I (referred to as AqBI) interface with a digital absolute BiSS interface. 6.1. AqBI Channel The AqBI channel provides incremental A-quad-B and Index signals. Signals A and B are electrically 90 out of phase with each other. The term quadrature refers to this 90 phase relationship. B leads A when counting up. 6.1.1. A & B Signals and Quadrature Up Down Counting The AqBI waveform, with the encoder moves in the positive direction as shown in FIGURE 6-8 FIGURE 6-8 AqBI waveform AN101_AqBiSSInterface_01.doc Copyright 2003 Netzer Precision Motion Sensors Ltd. Page 18 of 18

- APPENDIX A: DETAILED DESCRIPTION OF THE AQBISS INTERFACE - Since each full cycle contains four transitions, or edges, an encoder that generates 2000 cycles/rev, for example, provides 8,000 transitions per revolution. Each transition generates a count as well, indicating the direction of travel, which determines whether to count up or down. This is done by establishing whether the transition is going high or going low, and what the state of the other signal is, as shown in FIGURE 6-8. 6.1.2. Index The index is a separate output signal that produces a single pulse (or transition change) at a unique positions. The index is used to identify one or more reference positions. 6.2. BiSS Channel The Bidirectional digital sensor interface (BiSS) safeguards communication between position encoders or measuring devices and industrial controls, such as a drive control, for example, and if necessary can transmit measurement values from up to 8 sensors simultaneously. BiSS is an open industry standard that is gaining in popularity due to its low cost, high performance, and fewer required signal lines. BiSS is currently licensed free of charge. For more information, see http://www.biss-interface.com. FIGURE 6-9 Point-to-point BiSS application (source: STA - http://www.bissinterface.com/) AN101_AqBiSSInterface_01.doc Copyright 2003 Netzer Precision Motion Sensors Ltd. Page 19 of 19

- APPENDIX A: DETAILED DESCRIPTION OF THE AQBISS INTERFACE - 6.2.1. Advantages of BiSS Process information is directly digitized in the encoder, resulting in: high interference immunity the controller does not require analog interference suppression filters Transmitting and receiving electronics are simplified: no analog drivers and receivers no bidirectional driver components on both sides for encoder parameterization Serial data transmission ensures: compact 2 signals (4 lines) fast and suitable for real time control 10Mbit/sec and up to 100 meter cable highly reliable differential lines, line delay compensation, and CRC less connectors Development is simplified: lower design costs less board space requirement for electronics enabling more compact designs Minimal declarations are only required for register data for the paramaterization if an adaptive master needs to be supported. Otherwise, the instruction list is reduced to one write and one read instruction. After that, the BiSS protocol controls when and what datum has to be sent or received. The process is defined through time conditions, which are transmitted together with the clock. Operational parameters are available in the memory area of the slave. Furthermore, there are system parameters and in addition, should the occasion arise, OEM parameters that can be defined by the users. This also means that the encoder interface BiSS already meets the requirements for an electronic type label. In addition, the storage of temporary system data is conceivable in this area, e.g. the software-defined zero point of a rotary encoder. The data transmission is protected through a cyclic redundancy check (CRC). This means that each data packet is provided with a check sum, which is evaluated by the receiving device. 6.2.2. BiSS Specification BiSS is an open standard developed by ic-haus GmbH. For more information about BiSS, see http://www.biss-interface.com 6.2.3. Communication Modes and Signals The BiSS interface enables two communication modes: sensor mode - very fast data readout without requiring addressing With communication initialization, the master evaluates line delays and compensates automatically. The master then continues the clock signal necessary to output the slave AN101_AqBiSSInterface_01.doc Copyright 2003 Netzer Precision Motion Sensors Ltd. Page 20 of 20

- APPENDIX A: DETAILED DESCRIPTION OF THE AQBISS INTERFACE - encoder data (FIGURE 6-10). To ensure the absence of faults of the transmitted data, a hardware based error check is advisable. MA START CLK STOP SL ACK START DATA* MCD* STOP FIGURE 6-10 Sensor mode read cycle (* includes error checking) register mode - write and read transfers to individually addressable subscriber registers. BiSS provides a special addressing sequence (FIGURE 6-11) where 3 bits are used for the subscriber addressing and 7 bits are used for the register addressing. For increased reliability, the addressing sequence is protected by a 4-bit CRC. MA START ID ADR WNR CRC STOP SL ID LOCK FIGURE 6-11 Signals in register mode address sequence The 7 bits for the register addressing allow access to 128 registers of 8 bits each per encoder. If this address range is not sufficient, additional blocks of 128 registers can be added to a slave, with each additional block reducing the number of slaves available within the system by one. For reading data out of a register (FIGURE 6-12), the master has only to provide the corresponding number of clocks after the addressing sequence. During write access to the registers (FIGURE 6-13), the master transmits the data to be registered as PWM-coded data. MA START CLK STOP SL START REG DATA read back CRC STOP FIGURE 6-12 Signals in register mode read access MA START REG DATA write CRC STOP SL START REG DATA read back CRC STOP FIGURE 6-13 Signals in register mode write access Switching between the modes is performed through a time condition at the start of each communication cycle. AN101_AqBiSSInterface_01.doc Copyright 2003 Netzer Precision Motion Sensors Ltd. Page 21 of 21

- APPENDIX A: DETAILED DESCRIPTION OF THE AQBISS INTERFACE - 6.3. AqBiSS Electrical Interface 6.3.1. Electrical Specifications All the interface signals are in accordance with the EIA RS-422 standard. 6.3.2. Electrical Interface Circuit FIGURE 6-14 illustrates the AqBiSS interface circuit. AN101_AqBiSSInterface_01.doc Copyright 2003 Netzer Precision Motion Sensors Ltd. Page 22 of 22

- APPENDIX A: DETAILED DESCRIPTION OF THE AQBISS INTERFACE - A+ Z A- B+ B- I+ Z Z I- MA+ Z SL+ Z MA- SL- Vc GND AqBiSS Encoder Controller Circuit notes: FIGURE 6-14 AqBiSS interface circuit Termination resistor s (Z) value is 120 Ohm ±5%. Any RS-422 line transmitters and receivers that meet the requirements of the EIA standard may be used. AN101_AqBiSSInterface_01.doc Copyright 2003 Netzer Precision Motion Sensors Ltd. Page 23 of 23

- APPENDIX A: DETAILED DESCRIPTION OF THE AQBISS INTERFACE - 6.3.3. Pin Assignment The AqBiSS connector type may vary depending on the product model. TABLE 6-4 AqBiSS Pin Assignment Pin Signal Description Note 1. Vc 5V Power Supply 2. GND Ground (return Power Supply) 3. A+ A positive (AqB), output 4. A- A negative (AqB), output 5. B+ B positive (AqB), output 6. B- B negative (AqB), output 7. I+ Index positive (AqB), output 8. I- Index negative (AqB), output 9. MA+ Master positive (BiSS clock), input 10. MA- Master negative (BiSS clock), input 11. SL+ Slave positive (BiSS data), output 12. SL- Slave negative (BiSS data), output Twisted pair Twisted pair Twisted pair Twisted pair Twisted pair Twisted pair 6.3.4. Cable Cable requirements: Shielded, twisted pair, connected to chassis ground at both ends Connector-specific wire requirements: AWG26 AWG32 Note: if a long cable is used, then in order to avoid voltage excessive drop on the 5V supply, it is recommended to: a. Use cable with maximum gage possible in order to minimize resistance b. Use a separate power supply with short cable. 6.4. BiSS Master Controller Requirements The BiSS master at the controller end of the AqBiss interface can be one of the following: generic chip, for example the ic-haus ic-mb3 BiSS Interface Master, Netzer Precision s AqBiSS-to-RS232 converter AN101_AqBiSSInterface_01.doc Copyright 2003 Netzer Precision Motion Sensors Ltd. Page 24 of 24

- APPENDIX A: DETAILED DESCRIPTION OF THE AQBISS INTERFACE - 6.5. Memory Structure The NetzerAqBiSS Electric Encoder's EEPROM A8 (FIGURE 1-2) has addresses ranging from 00H to 7FH (127 bytes) and is accessible via the BiSS channel of the AqBiSS interface. The common address mapping is detailed in FIGURE 6-15, The user can write only from 20 to 5F. All other addresses are reserved. For more details regarding the registers refer to Application note AN102, AqBiSS Electric Encoder - calculating absolute position BiSS Address Hex 7F Encoder Signature Serial EEPROM 60 5F Optional Data 20 1F 10 0F 00 User Storage Area Power on Encoder Setup S/D Registers Legend: Not accessible to user: Accessible to user: FIGURE 6-15 Encoder EEPROM addresses AN101_AqBiSSInterface_01.doc Copyright 2003 Netzer Precision Motion Sensors Ltd. Page 25 of 25