MID-7604/7602 Stepper Power Motor Drive User Guide
8
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Host Bus Interlock Circuit
The MID-7604/7602 has a host bus interlock circuit that monitors the presence of +5 V from the host
computer and disables the MID-7604/7602 when the voltage is not present or falls out of tolerance. This
circuit shuts down the stepper drives for all axes by activating the inhibit when the host computer is
disconnected from the MID-7604/7602 or inadvertently shut down. Activation of the host bus interlock
circuitry illuminates the yellow LEDs (middle row) and red LEDs (top row) of the LED status array for
all axes. Refer to the
section of this guide for more information.
Note
In older versions of the MID-7604/7602, the red status LEDs do not illuminate when the
yellow status LEDs illuminate. This behavior only occurs in newer versions of the MID-7604/7602.
Front Panel LEDs
The front panel LEDs consist of a single green LED to indicate if the main power is active and an LED
status array of 3 rows by 4 columns that provides a variety of status information. Refer to Figure 1 for
the location of the front panel LEDs.
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.
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 axis and corresponding status for
each LED in the 3 × 4 array.
Driver Fault Output LEDs
The top row of LEDs indicates the status of the stepper drivers. An LED illuminates red when an
overcurrent condition or a problem with the motor bus voltage on that axis occurs. The LEDs also
illuminate red when the axis is inhibited. Refer to the
section of this guide for more
information about inhibit conditions.
Note
In older versions of the MID-7604/7602, the red status LEDs do not illuminate when the
yellow status LEDs illuminate. This behavior only occurs in newer versions of the MID-7604/7602.
Driver Inhibit LEDs
The middle row of LEDs indicates whether or not a motor axis is inhibited. An axis is inhibited and the
LED illuminates yellow in the following instances:
•
if the host bus interlock circuitry is activated
•
if the
ENABLE
switch on the front panel is in the inhibit (off) position
•
if the motion controller’s inhibit signal is low
•
if the per-axis inhibit input is actively driven
Table 1.
Front Panel LED Indicators
Status
Motor Axis
Driver Fault Output (red)
1
2
3
4
Driver Inhibit (yellow)
1
2
3
4
Limit Status (green)
1
2
3
4