Controller N1200
NOVUS AUTOMATION
11 / 13
The methods of
automatic tuning
and
auto-adaptative tuning
are
appropriate for most of the industrial processes. However, there may
be processes or even specific situations where the methods are not
capable to determine the controller's parameters in a satisfactory
way, resulting in undesired oscillations or even taking the process to
extreme conditions. The oscillations themselves imposed by the
tuning methods may be intolerable for certain processes. These
possible undesirable effects must be considered before beginning
the controller's use, and preventive measures must be adopted in
order to assure the integrity of the process and users.
The “
TUNE
” signaling device will stay on during the tuning process.
In the case of PWM or pulse output, the quality of tuning will also
depend on the cycle time adjusted previously by the user.
If the tuning does not result in a satisfactory control, refer to
Table 8
for guidelines on how to correct the behavior of the process.
PARAMETER
VERIFIED PROBLEM
SOLUTION
Proportional Band
Slow answer
Decrease
Great oscillation
Increase
Rate of Integration
Slow answer
Increase
Great oscillation
Decrease
Derivative Time
Slow answer or instability
Decrease
Great oscillation
Increase
Table 8 -
Guidance for manual adjustment of the PID parameters
MAINTENANCE
PROBLEMS WITH THE CONTROLLER
Connection errors and inadequate programming are the most
common errors found during the controller operation. A final revision
may avoid loss of time and damages.
The controller displays some messages to help the user identify
problems.
MESSAGE
DESCRIPTION OF THE PROBLEM
----
Open input. No sensor or signal.
Err1
Err6
Connection and/or configuration errors. Check
the wiring and the configuration.
Other error messages may indicate hardware problems requiring
maintenance service. When contacting the manufacturer, inform the
instrument serial number, obtained by pressing the key
for more
than 3 seconds.
CALIBRATION OF THE INPUT
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)
Configure the type of input to be calibrated.
b)
Configure the lower and upper limits of indication for the
maximum span of the selected input type.
c)
At the input terminals inject a signal corresponding to a known
indication value a little above the lower display limit.
d)
Access the parameter “
inLC
”. With the keys
and
adjust the
display reading such as to match the applied signal. Then press the
P
key.
e)
Inject a signal that corresponds to a value a little lower than the
upper limit of indication.
f)
Access the parameter “
inLC
”. With the keys
and
adjust
the display reading such as to match the applied signal. Then
press the
P
key.
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
Configure I/O 5 for the current output to be calibrated, be it
control or retransmission.
In the screen “
Ctrl
”, program manual mode (
man
).
Connect a current meter to the analog output.
Enter the calibration cycle with the correct password.
Select the screen “
ovLC
”. Press the keys
and
for the
controller to recognize the calibration process of the current
output.
Read the current indicated on the current meter and adjust the
parameter “
ovLC
” to indicate this current value (use the keys
and
)
Select the screen “
ovxC
”. Press the keys
and
for the
controller to recognize the calibration process of the current
output.
Read the current indicated on the current meter and adjust the
parameter “
ovkC
” to indicate this current value
Press the key
P
in order to confirm the calibration procedure
and return to the operating level.
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 indicator 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
.
Selectable speed; 8 data bits; 1
stop
bit; selectable parity (no
parity, pair or odd);
Time at the beginning of response transmission: maximum 100
ms after receiving the command.
There is
no electrical isolation
between serial communication
(RS485) and channel I/O5.
The RS-485 signals are:
D1 D D + B
Bi-directional data line.
Terminal 16
D0
D - A
Bi-directional inverted data line.
Terminal 17
C
Optional connection that improves the
performance of the communication.
Terminal 18
GND
CONFIGURATION OF PARAMETERS FOR SERIAL COMMUNICATION
Two parameters must be configured for using the serial type:
bavd:
Communication speed.
prty:
Parity of the communication.
addr:
Communication address for the controller.
D:
