Controller N2000
NOVUS AUTOMATION
10/11
AUTO TUNE
During auto tune the process is controlled in ON/OFF mode at the
programmed SetPoint (SV). Depending on the process
characteristics large oscillations above and below SV may occur and
auto tuning may take several minutes to be concluded.
The recommended procedure is as follows:
•
Disable the control output at the
rvn
prompt by selecting NO.
•
Select auto mode operation at the
Avto
prompt by selecting
YES.
•
Disable the ramp and soak function (select NO) and program a
new SV value other than the present PV (close to the desired set
point).
•
Enable auto tuning at the
Atvn
prompt by selecting YES.
•
Enable the control output at the
rvn
prompt by selecting YES.
•
The “TUNE” indicator on the display stays lit until the completion
of the automatic tuning process.
•
For control output types relay or pulse, the automatic tuning
calculates the longest suitable period (cycle time
(t
) for the
PWM output. The cycle time period may be reduced if the
process experiences some oscillation. When driving a SSR, it’s
recommended to set
(t
= 1 s.
•
If the automatic tuning does not result in a satisfactory control,
refer to Table 6 for guidelines on how to correct the behavior of
the process.
PARAMETER
RESPONSE
SOLUTION
Proportional Band
Slow Response
Decrease
Large Oscillation
Increase
Integral Rate
Slow Response
Increase
Large Oscillation
Decrease
Derivative Time
Slow Response or Instability
Decrease
Large Oscillation
Increase
Table 6 - Suggestions for manual tuning of PID parameters
CALIBRATION
INPUT CALIBRATION
All inputs are factory calibrated and recalibration should only be done
by qualified personnel. If you are not familiar with these procedures
do not attempt to calibrate this instrument. The calibration steps are:
a) Select the input type to be calibrated.
b) Set the desired upper and lower display limits.
c) At the input terminals inject an electrical signal corresponding to
a known indication value a little higher than the lower display
limit.
d) Select the
inL(
prompt. Through the and keys adjust
PV so that it matches the injected signal.
e) Inject a signal that corresponds to a value a little lower than the
upper limit of the display.
f) Select the
ink(
prompt. Through the and keys adjust
PV so that it matches the injected signal.
g) Repeat steps c) to f) to improve calibration.
Note: When checking the controller calibration with a Pt100
simulator, pay attention to the simulator minimum excitation current
requirement, which may not be compatible with the 0.170 mA
excitation current provided by the controller.
ANALOG OUTPUT CALIBRATION
1) Select type 11 or 12 at the I/O5 prompt.
2) Connect a current meter at the analog output.
3) Disable the auto-tune and soft-start functions.
4) Set the output low limit
ovLL
to 0.0 % and the output high limit
ovkL
to 100.0 %.
5) Select the manual mode at the
avto
prompt.
6) Enable the output at the
rvn
prompt.
7) At the operation cycle, set the MV to 0.0 %.
8) At the output low calibration
ovLC
prompt, press the
and
key until the mA meter reads zero mA. Approach this value from
above.
9) Set 100.0 % for the manipulated variable (MV).
10) At the output high calibration
ovkC
prompt, press the
and
key until the mA meter reads 20 mA. Approach this value
from below.
11) Repeat steps 7) to 10) as necessary.
PROBLEMS WITH THE CONTROLLER
Connection errors and inadequate programming are the most
common errors found during the controller operation. A final review
may avoid loss of time and damages.
The controller displays some messages to help the user identify
problems.
MESSAGE
PROBLEM
----
Open input. Without sensor or signal.
Err1
Err6
Configuration or connection problem in the Pt100
cable
Other error messages displayed by the controller can account for errors
in the input connections or type of selected input non-compliant with the
sensor or signal applied to the input. If errors persist, even after a
review, contact the manufacturer. Inform also the device serial number.
To find out the serial number, press
for more than 3 seconds.
The controller also has a visual alarm (the display flashes) when the
PV value is out of the range set by
spxl
and
spll
.
SERIAL COMMUNICATION
The controller can be supplied with an asynchronous RS-485 digital
communication interface for master-slave connection to a host
computer (master).
The controller works as a slave only and all commands are started by
the computer which sends a request to the slave address. The
addressed unit sends back the requested reply.
Broadcast commands (addressed to all controller units in a multidrop
network) are accepted but no reply is sent back in this case.
CHARACTERISTICS
•
Signals compatible with RS-485 standard. MODBUS (RTU)
Protocol. Two wire connection between 1 master and up to 31
(addressing up to 247 possible) instruments in bus topology. The
communication signals are electrically insulated from the rest of
the device;
•
Maximum connection distance: 1000 meters.
•
Time of disconnection for the controller: Maximum 2 ms after last
byte.
•
The communication signals are electrically isolated from the rest
of the instrument, and can be 1200, 2400, 4800, 9600 and 19200
bps.
•
Number of data bits: 8, without parity or pair parity. Number of
stop bits: 1
•
Time to start response transmission: up to 100 ms after
acknowledging the command.
