RAMK060

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Vishay MCB

Revision: 03-May-2022

8

Document Number: 32579

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OPTIONAL MULTI-TURNS COUNTER

First Possible Option: Counting of Turns Without Battery Backup Connector and Memorization of Last Position Before

Power Off!

In normal operation when the power is on, the counting of the turns is made in the two directions, clockwise and anticlockwise.

The maximum value of the counter is -32 768 anticlockwise turns to +32 767 clockwise turns. When the counter reaches the

maximum value of 32 767, the next counter value is set to -32 768. When it reaches the minimum value of -32 768, the next

value is set to 32 767.

The value of the turn counter is sent in the output frame in two complement. No counting during power off. When the power is

off, the last position before power cutting (value of the multi-turn counter and value of the angle) is memorized in a no volatile

memory and the encoder can accept (during power off) a movement of encoder up to ± 90° to calculate and release the new

position as soon as the power comes back.

The number of non-volatile memory in write-in cycles is unlimited.

At the power on, if the variation of the angle is superior to ± 90°, the error flag of the frame is set and the multi-turn counter is

reset at the next power on. This procedure could be used to reset the multi-turns counter.

The multi-turns counter is also reset when the sensor enter in the self-calibration mode.

Second Possible Option: Counting of Turns With Battery Backup Across Connector

After the power off, if the sensor turns, the number of revolutions are counted internally. The counting is made in the two

directions, clockwise and anticlockwise. The maximum value of the counter is -32 767 anticlockwise turns to +32 767 clockwise

turns. When the counter reaches the maximum value of 32 767, the next counter value is set to -32 768. When the counter

reaches the minimum of -32 768, the next value is set to 32 767.

During the power is off, no data is sent to the output. With the backup battery connector plugged to external battery, with low

consumption, the encoder counts the number of turns and stocks this data in memory. As soon as the power comes back, the

encoder releases the data of number of turns and continues to count in normal conditions.

The multi-turns counter is also reset when the sensor enter in the self-calibration mode.

MULTI-TURNS SSI OUTPUT FORMAT

Fig. 6 - SSI Multi-Turns Chronogram

Note

• Bit 38 always = 0

TABLE 10 - SSI MULTI-TURN DATA BITS FORMAT

SSI DATA BITS FORMAT

DATA BIT

MSB

LSB

DATA BITS LENGTH

INFORMATION

Status bits

Frame bit 0

Frame bit 2

3 bits

See section “Self-Monitoring”

Multi-turns counter

Frame bit 3

Frame bit 18

16 bits

See Fig. 6

Angle value

Frame bit 19

Frame bit 37

19 bits

See Table 3

Parity

Frame bit 39

-

1 bit

A1

A2

A3

MSB

LSB

MSB

LSB

P

Time out

01

2

3

39

20

SSI

CLK+

CLK-

DATA+

DATA-

419

18

38

21

37

≥ 1 μs

t = 20 μs

tclk