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120  Unidrive SPM User Guide
www.controltechniques.com                               Issue Number: 3
ANSIx3.28 protocol
Full details of the CT ANSI communications protocol are the Advanced 
User Guide.
Modbus RTU protocol
Full details of the CT implementation of Modbus RTU are given in the 
Advanced User Guide.
Modbus RTU protocol, but with an SM-Keypad only
This setting is used for disabling communications access when the SM-
Keypad is used as a hardware key. 
* only applicable to Modbus RTU mode
This parameter can be changed via the drive keypad, via a Solutions 
Module or via the comms interface itself. If it is changed via the comms 
interface, the response to the command uses the original baud rate. The 
master should wait at least 20ms before send a new message using the 
new baud rate.
Used to define the unique address for the drive for the serial interface. 
The drive is always a slave. 
Modbus RTU 
When the Modbus RTU protocol is used addresses between 0 and 247 
are permitted. Address 0 is used to globally address all slaves, and so 
this address should not be set in this parameter
ANSI
When the ANSI protocol is used the first digit is the group and the 
second digit is the address within a group. The maximum permitted 
group number is 9 and the maximum permitted address within a group is 
9. Therefore, Pr 0.37 is limited to 99 in this mode. The value 00 is used 
to globally address all slaves on the system, and x0 is used to address 
all slaves of group x, therefore these addresses should not be set in this 
parameter. 
These parameters control the proportional and integral gains of the 
current controller used in the open loop drive. The current controller 
either provides current limits or closed loop torque control by modifying 
the drive output frequency. The control loop is also used in its torque 
mode during line power supply loss, or when the controlled mode 
standard ramp is active and the drive is decelerating, to regulate the flow 
of current into the drive.
Open-Loop
There are two autotune tests available in open loop mode, a stationary 
and a rotating test. A rotating autotune should be used whenever 
possible, so the measured value of power factor of the motor is used by 
the drive.
• The stationary autotune can be used when the motor is loaded and it 
is not possible to remove the load from the motor shaft. 
• A rotating autotune first performs a stationary autotune, before 
rotating the motor at 
2
/
3
 base speed in the forward direction for 
several seconds. The motor must be free from load for the rotating 
autotune.
To perform an autotune, set Pr 0.40 to 1 for a stationary test or 2 for a 
rotating test, and provide the drive with both an enable signal (on 
terminal 31) and a run signal (on terminal 26 or 27).
Following the completion of an autotune test the drive will go into the 
inhibit state. The drive must be placed into a controlled disable condition 
before the drive can be made to run at the required reference. The drive 
can be put in to a controlled disable condition by removing the SAFE 
TORQUE OFF (SECURE DISABLE) signal from terminal 31, setting the 
drive enable parameter Pr 6.15 to OFF (0) or disabling the drive via the 
control word (Pr 6.42 & Pr 6.43).
For further information refer to section  Pr 0.40 {5.12} Autotune on 
page 136.
Closed-loop
There are three autotune tests available in closed loop vector mode, a 
stationary test, a rotating test and an inertia measurement test. A 
stationary autotune will give moderate performance whereas a rotating 
autotune will give improved performance as it measures the actual 
values of the motor parameters required by the drive. An inertia 
measurement test should be performed separately to a stationary or 
rotating autotune.
• The stationary autotune can be used when the motor is loaded and it 
is not possible to remove the load from the motor shaft. 
• A rotating autotune first performs a stationary autotune, before 
rotating the motor at 
2
/
3
 base speed in the forward direction for 
approximately 30 seconds. The motor must be free from load for the 
rotating autotune.
• The inertia measurement test can measure the total inertia of the 
load and the motor. This is used to set the speed loop gains (see 
Comms value String Communications mode
0 AnSI ANSI
1 rtU Modbus RTU protocol
2Lcd
Modbus RTU protocol, but with an SM-
Keypad only
0.36 {11.25} Serial comms baud rate
RW Txt US
Ú
300 (0), 600 (1), 1200 (2), 
2400 (3), 4800 (4), 9600 (5), 
19200 (6), 38400 (7), 
57600 (8)*, 115200 (9)*
Ö
19200 (6)
0.37 {11.23} Serial comms address
RW Uni US
Ú
0 to 247
Ö
1
0.38 {4.13} Current loop P gain
RW Uni US
OL
Ú
0 to 30,000
Ö
All voltage ratings: 20
CL
ÚÖ
200V drive: 75
400V drive: 150
575V drive: 180
690V drive: 215
0.39 {4.14} Current loop I gain
RW Uni US
OL
Ú
0 to 30,000
Ö
All voltage ratings: 40
CL
ÚÖ
200V drive: 1,000
400V drive: 2,000
575V drive: 2,400
690V drive: 3,000
0.40 {5.12} Autotune
RW Uni
OL
Ú
0 to 2
Ö
0
VT
Ú
0 to 4
Ö
0
SV
Ú
0 to 6
Ö
0