NOVA electronics Inc.
MCX514 -
41
－
41
－
2.5
Automatic Home Search
This IC has a function that automatically executes a home search sequence such as high-
speed home search → low-speed home
search → encoder Z-phase search → offset drive without CPU intervention. The automatic home search function sequentially
executes the steps from Step1to Step4that are listed below. The user can select execution or non-execution for each step. If
non-execution is selected, it proceeds with next step without executing that step. And for each step, the user sets a search direction
and a detection signal by mode setting. In steps 1 and 4, search operation or driving is performed at the high-speed that is set in the
drive speed. In Steps2 and 3, search operation is performed at the low-speed that is set in the home search speed. In addition in
Steps2 and 3, it is possible to output nDCC (deviation counter clear signal) or clear the real/logical position counter when the
signal is detected. The timer between steps can be used at the end of each step.
Table 2.5-1 Details of Automatic Home Search Sequence
Step number
Operation
Search speed
Detection signal
Step 1
High-speed home search
Drive speed (DV)
Specify any one of nSTOP0, nSTOP1 and Limit
Step 2
Low-speed home search
Home search speed (HV)
Specify either nSTOP1 or Limit
Step 3
Low-speed Z-phase search
Home search speed (HV)
nSTOP2
Step 4
High-speed offset drive
Drive speed (DV)
－
Generally, automatic home search has various operations according to the detection signal that is used. As shown in the following
examples, there are some cases of a home search, such as using two sensors, a near home signal and a home signal, and using only
a home signal or only one limit signal.
(1) Example of the home search using a near home signal (nSTOP0) and a home signal (nSTOP1)
It searches a near home signal at high-speed in a specified direction, and then if a near home signal is detected, it performs
decelerating stop. Next, it searches a home signal at low-speed, and then if a home signal is detected, it performs instant stop.
Step1
Step2
High- speed home search
Low- speed home search
Instant stop at detection of Home
Active
Section
Decelerating stop
at detection of
Near Home
Near Home Sensor
Home Sensor
Fig. 2.5-1 Example 1 of Automatic Home Search
(2) Example of the home search using only a home signal (nSTOP1) or only one limit signal (nLMTP/nLMTM)
It searches a home signal or a limit signal at high-speed in a specified direction, and then if a signal is detected, it performs
decelerating stop. Next, it escapes in the opposite direction from the signal active section, and then searches a home signal at
low-speed, and if a home signal is detected, it performs instant stop. If a limit signal is used as a detection signal, it becomes the
limit signal of a search direction.
Home or Limit Sensor
Step1 High- speed home search
Step2 Low- speed home search
When the same direction is specified in Step1 and 2
Once Exit
search
Fig. 2.5-2 Example 2 of Automatic Home Search
This IC provides several mode settings in response to these various home search operations.
