Functions of the IM 178-4
6-7
IM 178-4
C79000-G7076-C178-01
Table 6-2
Overview of Position Encoder Errors
Type of Error
Sensors with
Which Error is
Possible
Possible Causes of the
Error
Reaction of the
IM 178-4
Start/stop bit error
Absolute posi-
tion encoder
(SSI)
S
Sensor cable not
connected
S
Break on the sensor cable
S
Parameters on the
IM 178-4 do not match the
connected sensor
S
Sensor defective
S
Interference
S
EXTF1 status
bit (sensor
error) is set
S
Last correct
actual value is
retained
Edge error
Incremental
sensor
Interference on the sensor
cable
EXTF1 status bit
(sensor error) is
set
Sensor signal
cable error
Absolute
position
encoder (SSI)
and
incremental
encoder
S
Wire break
S
Cable not plugged in
S
Short–circuit between
wires, to ground or to
sensor power supply
EXTF0 status bit
(sensor signal
cable error) is set
Zero mark monito-
ring error
Incremental
sensor
S
Interference on the sensor
cable
S
Sensor defective
S
EXTF2 status
bit (zero mark
error) is set
S
Synchroni-
zation is
cleared, SYNC
status bit is
reset
Zero Mark Monitoring
Zero mark monitoring is only possible when using an incremental sensor with at
least 4 increments (corresponds to 16 count pulses) per revolution. After assigning
parameters to the IM 178-4, zero mark monitoring is only active after successful
synchronization (synchronization condition rising edge of the zero mark or digital
input I1 and zero mark).