Omron NX-EC0112, Руководство пользователя

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7 SSI Input Units
7 - 22 NX-series Position Interface Units User’s Manual (W524)
When you use an NJ/NX-series Controller with the MC Function Module, you must set the Unit as an
encoder axis. Set the axis parameter settings and assign an axis variable from the Sysmac Studio.
Refer to the NJ/NX-series CPU Unit Motion Control User’s Manual (Cat. No. W507) for detailed setting
procedures.
Observe the following precautions when you use an SSI Input Unit with the MC Function Module.
• Connect the SSI Input Unit after an EtherCAT Coupler Unit.
• Set the coding method to present value conversion to use an SSI Input Unit as an incremental
encoder with a 32-bit counting range, regardless of the SSI encoder resolution. In this case, change
the setting as shown below according to the output data from the SSI encoder.
The present position of the encoder axis is obtained based on the encoder type setting in the axis
parameters of the MC Function Module, as described in the following table.
• The Unit is treated as an axis (encoder axis) from the user program, so you cannot handle the I/O
data from the SSI Input Unit directly. The Unit is handled as an axis variable.
• SSI communications must always be enabled to use an SSI Input Unit with the MC Function Module.
Do not assign the SSI Operation Command parameter to I/O data. SSI communications are enabled
by default if you do not assign the SSI Operation Command parameter to I/O data.
• For an NX-series CPU Unit, you can execute motion control in the primary periodic task and priority-5
periodic task.
• You cannot use motion control instructions to perform control operations.
Precautions for Correct Use
• The MC Function Module cannot directly manipulate SSI encoder absolute value data if the
coding method is set to present value conversion. In this case, you cannot use an encoder
axis as an infinite-length axis absolute encoder.
• When you use an SSI Input Unit with the MC Function Module, the MC Function Module
monitors the bit that corresponds to the SSI Input Unit in the Process Data Communications
Status. You can assign the Process Data Communications Status as an EtherCAT Coupler
Unit device variable. The MC Function Module calculates the initial position of the encoder
axis when this bit is first set. If there is an error in the SSI Input Unit at this time, the initial
position of the encoder axis is not set correctly.
Refer to the precautions in
7-6-6 Process Data Communications Status on page 7-26 and
write the user program.
Using an NJ/NX-series Controller with the MC Function Module
SSI encoder Setting
Binary code output Change binary codes to present values.
Gray code output Change gray codes to present values.
Encoder type Present position
Incremental encoder The present position of the encoder axis is 0 when the power is turned ON to the
Controller or when the Controller is restarted (i.e., when data starts being
exchanged with the Unit).
Absolute encoder The present position of the Unit is treated as the present position of the encoder
axis when the power is turned ON to the Controller or when the Controller is
restarted (i.e., when data starts being exchanged with the Unit).