NOVA electronics Inc.
MCX514 -
52
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52
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2.5.7
Notes on Automatic Home Search
■
Search speed
A home search speed (HV) must be set to a low speed to increase the home search position precision. Set a value lower than the
initial speed to stop the operation immediately when an input signal becomes active.
For the encoder Z-phase search of Step 3, the relationship between the Z-phase signal delay and the home search speed (HV)
becomes important. For instance, if a total of the photo coupler delay time of the Z-phase signal path and delay time of the integral
filter incorporated in the IC is the maximum 500
μ
sec, the home search speed must be set so that the encoder Z-phase output is
ON for more than 1msec.
■
Step 3 (Z-phase search) starting position
In the Z-phase search of Step 3, the function stops search driving when the Z-phase signal (nSTOP2) changes from inactive to
active. Therefore, the Step 3 starting position (that is, Step 2 stop position) must be stable and different from this change point.
Normally, adjust mechanically so that the Step 3 starting position becomes the 180
°
opposite side to the encoder Z-phase
position.
■
Software limit
Disable the software limit during the execution of automatic home search. If software limit is enabled, the automatic home search
is not performed correctly. After the automatic home search is finished correctly, set a software limit after setting the real / logical
position counter.
■
Logical setting of each input signal
Use the bits (WR2/D0,D2,D4) of WR2 register for the active logical setting of the input signal (nSTOP0,1,2) that is used by an
automatic home search. In an automatic home search, the settings in the bits (WR2/D1,D3,D5) that enable/disable each signal are
ignored.
