➄
Basic 6250 Features
45
6250 Safety Features
To help ensure a safe operating environment, you should take advantage of the 6250's safety
features (see table). See Also refers you to the section in this user guide where you can find
more in-depth information about the feature (system connections and/or programming
instructions).
F e a t u r e
Description
See Also
Enable Input
The enable input (
ENBL
), found on pin #14 on the
AUX
connector, is provided as an emergency stop input to the
6250.
When you open the
ENBL
input, with respect to
GND
, the
analog output voltage between
CMD+
and
CMD-
is clamped
to almost zero, and the shutdown outputs are activated on
both axes.
Clamping occurs independent of the
microprocessor and the DSP. (The clamping circuit is also
connected to the watchdog timer; if the 6250's
microprocessor fails, the analog output voltage will be
clamped.)
Chapter 3:
System
Connections
Shutdown
Outputs
The 6250 uses the shutdown outputs to disable the drive if it
detects a problem. Two types of relay outputs are found on
both
DRIVE
connectors—
SHTNC
for drives that require a
closed contact to disable the drive, and
SHTNO
for drives
that require an open contact to disable the drive.
The shutdown relay outputs are essential for smooth power-
up and power-down of the system. The shutdown relay is
active (disabling the drive) when no power is applied to the
6250. When the 6250 is powered up, the shutdown relay
remains active until you issue the
DRIVE11
command.
Chapter 3:
Motor Driver
Connections
Drive Fault
Inputs
The drive fault (
DFT
) inputs, found on pin #5 of both
DRIVE
connectors, allows the drives to tell the 6250 if they
encounter a fault condition. When a drive fault occurs, the
6250 stops motion (at the rate set with the
LHAD
command)
and terminates program execution. No drive shutdown will
result unless it is initiated with an
ERRORP
error program.
Chapter 3:
Motor Driver
Connections
End-of-travel
Limit Inputs
End-of-travel limits prevent the load from crashing through
mechanical stops, an incident that can damage equipment
and injure personnel.
You can use hardware or software limits, as your application
requires. Hardware limits use the
CW
and
CCW
terminals on
the
LIM1/2
connector. Software limits are set with the
LSCCW
and
LSCW
commands.
Chapter 5:
End-of-Travel
Limits
User Fault
Input
Using the
INFNCi-F
command, you can assign any of the
programmable inputs the
user fault function. You can then
wire the input to activate when an external event, considered
a
fault by the user, occurs.
Chapter 5:
Input
Functions
Maximum
Allowable
Position Error
A
position error (
TPER
) is defined as the difference between
the commanded position (
TPC
) and the actual position as
measured by the encoder (
TPE
). The maximum allowable
position error is set with the
SMPER
command. When the
maximum allowable position error is exceeded (usually due
to instability or loss of position feedback from the encoder),
the 6250 shuts down the drive and sets error status bit #12
(reported by the
TER
command).
If
SMPER
is set to zero (
SMPERØ
), the position error will not be
monitored.
Chapter 4:
Servo Tuning
☞
Programmed Error-
Handling Responses
When any of the safety features listed above are exercised (e.g.,
ENBL
input is opened,
DFT
input
is activated, etc.), the 6250 considers it an error condition. With the exception of the shutdown
output activation, you can enable the
ERROR
command to check for the error condition, and
when it occurs to branch to a preprogrammed response defined with the
ERRORP
command.
Refer to the Error Handling section in Chapter 7 for further information.
