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National Instruments Corporation
7
MID-7654/7652 Servo Power Motor Drive User Guide
Both the AC POWER and ENABLE switches can inhibit the servo amplifiers. However, as long as the
AC POWER switch is on, only the servo amplifier output stages are disabled. The remaining circuitry
remains active, including the quadrature encoder circuit.
Caution
You
must
change the MID-7654/7652 main input fuse on the rear panel if you change
the line voltage from the factory setting. Refer to the
section of this guide for fuse
specifications. Refer to the
Modifying the Power Entry Module
section for more information on
handling the power entry module.
Host Bus Interlock Circuit
The MID-7654/7652 has a host bus interlock circuit that monitors the presence of +5 V from the host
computer and disables the MID-7654/7652 when the voltage is not present or falls out of tolerance. This
circuit shuts down the servo amplifiers for all axes by activating the inhibit when the host computer is
disconnected from the MID-7654/7652 or inadvertently shut down. Activation of the host bus interlock
circuitry illuminates the yellow LEDs (middle row) of the LED status array for all axes. See the
section of this guide for more information.
Front Panel LEDs
The front panel LEDs consist of a single green LED to indicate if the main 5 V power is active. If the
DC power supplies are active, the green power LED illuminates. If this LED fails to illuminate, check
the power cord and the main input fuse on the front panel.
An LED status array of 3 rows by 4 columns on the MID-7654 or 3 rows by 2 columns on the MID-7652
provides a variety of status information. Refer to Figure 1 for the location of the front panel LEDs. The
LED status array is arranged by motor axes. Each of the four columns represents an axis, and each of
the three rows represents a particular status. Table 1 summarizes the axes and statuses to which the
different LEDs in the 3 × 4 or 3 × 2 array correspond.
Amplifier Fault Output LEDs
The top row of the LED status array indicates the status of the amplifiers. A red LED indicates an
overcurrent condition, a short circuit condition, an over temperature condition, or a problem with the
motor bus voltage on that axis.
Amplifier Inhibit LEDs
The middle row of the LED status array indicates if a motor axis is inhibited. An axis is inhibited and
the LED illuminates yellow if the host bus interlock circuitry is activated from the back panel, if the
ENABLE switch on the front panel is in the inhibit position, if the motion controller’s inhibit signal is
low, or if the per-axis inhibit input is actively driven. You can select the polarity of the per-axis inhibit
input from the front panel DIP switches. See the
Front Panel DIP Switch Settings
section of this guide
for more information.
Table 1.
Front Panel LED Indicators
Status
Motor Axis
Amplifier Fault Output (red)
1
2
3
*
4
*
Amplifier Inhibit (yellow)
1
2
3
*
4
*
Limit Status (green)
1
2
3
*
4
*
*
These LEDs only appear on the MID-7654.
