IM 12D08N05-01E
5-6
<5. MENU STRUCTURE COMMISSIONING>
5.6 mA output setup
The general procedure is to first define the function (control, output, simulate, off) of the
output and second the process parameter associated to the output.
Available process parameters depend on selected “sensor type” and “measurement
setup”.
Off :
When an output is set off the output is not used and will give an output of 4
mA
Control :
A selection of P- PI- or PID control
Manual :
Static output required to maintain reset equilibrium state with setpoint
Direction :
Direct.
If the process variable is too high relative to the SP, the output of the
controller is increased (direct action).
Reverse.
If the process variable is too high relative to the SP, the output of the
controller is decreased (reverse action).
Output :
Linear or non linear table output.
The table function allows the configuration of an output curve by 21 steps
(5% intervals). In the main menu concentration can be selected to set the
concentration range.
Simulate :
Percentage of output span.
Normal span of outputs are limited from 3.8 to 20.5 mA
Fail safe :
Contact S4 is programmed as a fail-safe contact.
Burn Low or High will give an output of 3.6 resp. 21 mA in case of Fail situation.
NOTE
When leaving Commissioning, Hold remains active until switched off manually. This is to
avoid inappropriate actions while setting up the measurement.
l
Proportional control
Proportional Control action produces an output signal that is proportional to the difference
between the Setpoint and the PV (deviation or error). Proportional control amplifies the
error to motivate the process value towards the desired setpoint. The output signal is
represented as a percentage of output (0-100%).
Proportional control will reduce but not eliminate the steady state error. Therefore,
proportional Control action includes a Manual Reset. The manual reset (percentage of
output) is used to eliminate the steady state error.
NOTE
Any changes (disturbances) in the process will re-introduce a steady state error.
Proportional control can also produce excessive overshoot and oscillation. Too much gain
may result in an unstable- or oscillating process. Too little gain results in a sustained steady
state error.
Gain = 1/Range. [PV units]
