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Reference Manual
IP2030/RM, Rev AA
Section 4: Getting started
June 2014
Section 4: Getting started68
4.5.20 Set-up the current output
The Current Output is for transmitting the control unit PV value (D800) as a 4–20 mA signal.
The output is calculated by using the range values of parameters P400 and P401.
Example
Consider a control unit PV value of 5 metres and the PV range is 0 to 10 metres:
0 metres is represented by a 4 mA signal (0%)
5 metres is represented by a 12 mA signal (50%)
10 metres is represented by 20 mA signal (100%)
Therefore, the Current Output would output the PV value 5 metres as a 12 mA signal.
Note
The current output is frozen while the control unit is in the Program operating mode.
Menu: SETUP / [CONTROLLER /] OUTPUT / CURRENT OUTPUT
P400 Low Range Val (Factory default is 0.0)
This is the minimum control unit PV value represented by 4 mA.
P401 Up Range Val (Factory default is 100.0)
This is the maximum control unit PV value represented by 20 mA.
P402 Alarm Actions (Factory default is 3.6 mA)
Optional for determining how an alarm, if selected in the ALARM menu, is indicated on
the Current Output. Options for P402 are:
3.6 mA – fix current output to 3.6 mA to force a low current limit alarm.
Hold – freeze the current output at the present value.
21 mA – fix current output to 21 mA to force high current limit alarm.
See also Table 4-8 on page 94 for a summary of reporting methods for Alarms.
Note
The 3.6 mA and 21 mA options are the Mobrey Standard.
There is another alarm condition when the current output has reached the linear limit
i.e. saturated. For the Mobrey Standard, this is 3.8 mA or 20.5 mA.
P404 mA Mode (Factory default is “Instantaneous”)
On the Mobrey MCU90F, this optional parameter is for assigning the Current Output to
follow a rolling average of the calculated control unit PV (typically flow). To do this,
select the Rolling option.
The time period for the rolling averaging is defined using P590, which is also for
defining the logging interval (see “Data logging on the Mobrey MCU90F” on page 64).