Mitsubishi Electric QD75P1N User Manual page 538

12 CONTROL SUB FUNCTIONS
12.3.2 Electronic gear function
The "electronic gear function" adjusts the pulses calculated and output according to the
parameters set in the QD75 with the actual machine movement amount.
The "electronic gear function" has the following four functions.
[A] The function converts the command value (speed, movement amount from the
start point to the end point), which is set in mm units, to pulse units, and
determines the pulse frequency and pulse number of the command pulse.
CPU module,
GX Configurator-QP
1: Unit specified with " Pr.1 Unit setting" (mm, inch, degree, pulse)
[B] If values less than one pulse are generated by converting the movement
amount from the start point to the end point to pulse units, the values are not
output and the machine stops at the front side of the positioning direction. The
function accumulates values less than one pulse that could not be pulse
output in the QD75 and outputs one pulse when the total cumulative value
reached one pulse or more.
[C] When machine OPR is completed, current value changing is completed,
speed control is started (except when current feed value change is present), or
fixed-feed control is started, the function clears to "0" the cumulative values of
less than one pulse which could not be output. (If the cumulative value is
cleared, an error will occur by a cleared amount in the feed machine value.
Control can be constantly carried out at the same machine movement amount,
even when the fixed-feed control is continued.)
[D] The function compensates the mechanical system error of the command
movement amount and actual movement amount by adjusting the "movement
amount per pulse".
(The "movement amount per pulse" value is defined by " Pr.2 No. of pulses
per rotation (Ap)", " Pr.3 Movement amount per rotation (Al)", and
" Pr.4 Unit magnification (Am)".)
The QD75 automatically carries out the processing for [A] and [C].
The details shown below explain about the "electronic gear function", including the
method for compensating the error in [D] above, etc.
[1] Movement amount per pulse
[2] Error compensation method
[3] Control Precautions
QD75
Command value
Electronic
gear
Set value in each unit *1.
Speed: V
Movement amount: L
Fig. 12.9 Conversion to pulse units
12 - 14
MELSEC-Q
Command output pulses
Speed: Frequency
Movement amount: Number
of pulses