5 Troubleshooting
 
5
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Er.B01: Pulse input abnormal
Cause Conrming Methods Corrective Action
1. Input pulse 
frequency is greater 
than H0A-09 
(Maximum position 
pulse frequency).
Check whether H0A-09 is 
smaller than maximum input 
pulse frequency required by 
normal machine running.
Reset H0A-09 correctly according to the actual 
requirement.
If output pulse frequency of host computer is larger than 
4 MHz, decrease it.
2. Input pulse suffers 
interference.
Check whether position 
reference increases abruptly 
or whether H0B-13 (input 
reference pulse counter) is 
larger than the number of 
pulses output by host computer 
through oscilloscope.
Then check grounding situation 
of connecting cables.
First, use an STP cable for pulse input and separate 
pulse input cable from servo drive power cables.
Then, when differential input is selected on the 
condition of using low-speed pulse input terminal (H05-
01 = 0), ground of host computer must be connected 
to GND of servo drive reliably. If open-collector input is 
selected, ground of host computer must be connected 
to COM of servo drive reliably. Only differential input 
can be selected on the condition of using high-speed 
pulse input terminal (H05-01 = 1), ground of host 
computer must be connected to GND of servo drive 
reliably.
Finally, according to selected hardware input terminal, 
increase pin lter time of pulse input terminal in H0A-24 
or H0A-30.
Er.B02: Position deviation being too large in full closed-loop
Cause Conrming Methods Corrective Action
1. Power output phase 
(UVW) loss or incorrect 
phase sequence occurs 
on servo drive.
Perform motor trial running when there is no load 
and check motor wirings.
Connect wirings correctly again or 
replace them.
2. UVW cable or 
internal/external 
encoder cable breaks.
Check wirings.
Reconnect the UVW cable. Power 
cables of servo motor and power 
cables UVW of servo drive must 
be one-to-one correspondence. If 
necessary, replace a new cable and 
ensure reliable connection.
3. Motor rotor is locked 
due to mechanical 
factors.
Check running reference and motor speed (H0B-
00) by using the drive debugging platform of 
Inovance or operating panel.
Running reference in the position control mode: 
H0B-13 (input reference pulse counter)
Running reference in speed control: H0B-01 
(speed reference)
Running reference in torque control: H0B-02 
(internal torque reference)
Check running reference in corresponding mode is 
not 0 but the motor speed is 0.
Eliminate mechanical factors.
4. Servo drive gain is 
low.
Check servo drive position loop gain and speed 
loop gain.
First gain: H08-00 to H08-02
Second gain: H08-03 to H08-05
Adjust gain manually or perform 
automatic gain auto-tuning 
according to Chapter 6 in the 
IS650P User Manual.