Omron NX-EC0112, User Manual

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7 SSI Input Units
7 - 40 NX-series Position Interface Units User’s Manual (W524)
You can connect an SSI Input Unit to the following types of encoders.
• A single-turn encoder that performs single-turn position detection
• A multi-turn encoder that can count the number of rotations
• An encoder that reports the position data and status data
The encoder’s position data and status data are synchronized with the clock signal and transferred over
the data line.
You can set the bit positions and bit lengths for multi-turn data, single-turn data, and status data. You
can also set the start bit position data for position data and status data.
This enables you to support a variety of encoders with different status data positions or when additional
information is added in front of or behind the position data.
However, the total bit length of all the data must not exceed 32 bits. The bit position plus data length of
any data must not exceed 32 bits.
Use the following equation to calculate the actual present position to send to the Controller.
• Actual present position = Previous present po Travel distance
However, the calculation method depends on the code conversion that you used. Refer to 7-9-3 Coding
Method on page 7-44 for information on code conversion.
7-9-2 SSI Data Settings
Data frame: 1 to 32 bits
Conversion Wait Time
Clock
Data
MSB LSB
Wait Time
for Receive
Enabled
Leading
bits
Single-turn Data
Start Bit
Multi-turn
Data Start Bit
Status Data Start
Bit
SSI
Communications
Startup Time
Monoflop Time
Status data Multi-turn data Single-turn
data
Power cycled or NX
Unit restarted.