FEC920: USER GUIDE
Page 81
September 18
6.5 VIRTUAL CHANNEL CONFIGURATION
This allows the configuration of maths channels, totalizers and counters. The configuration is divided into the
following areas: ‘Main’, ‘Trend’, ‘Alarm 1*’ and ‘Alarm 2*’. Items appearing in the ‘Trend’, Alarm 1’ and ‘Alarm 2’
areas are identical with the equivalent items described in Section 6.4 (Input channels), above.
6.5.1 Maths channel configuration
The following maths functions are available (listed in up-arrow scroll order)
Off, Add, Subtract, Multiply, Divide, Group Average, Group minimum, Group maximum, Modbus input, Copy,
Group minimum (latch), Group maximum (latch), Channel maximum, Channel minimum, Channel Average,
Configuration revision, Off.
Figure 74 shows a typical maths channel configuration.
Figure 74 Maths channel configuration (typical)
Descriptor
Allows the user to enter a descriptor (20 characters max.) for the maths channel
Type
Math selected for this example. See Section 6.5.2 and Section 6.5.4 for totalizers and
counters respectively.
Operation
Allows the user to select the required maths function. See ‘Maths Functions’, below.
PV
Read-only. Shows the dynamic value of this channel in the units entered in ‘Units’ below.
Status
Read-only. Shows the status of this channel, reflecting the status of the input sources.
Resolution
Enter the number of decimal places required
Units
Allows a five character string to be entered to be used as the channel units.
Input1
The value of input 1. May be entered manually, or it may be wired from another parameter
(Section 9). Uses the resolution of the source.
Input 2
As for ‘Input 1’, Appears only when the operation requires two inputs.
Reset
Allows the user to reset latching functions (e.g. Channel Max) or averaging functions (e.g.
Channel Avg). Reset is carried out by setting the field to ‘Yes’, then operating the scroll
key. The display returns to ‘No’. Alternatively the function can be reset by another
parameter wired to ‘Reset’.
Time Remaining
The period of time remaining before the virtual channel performs its operation. For
example, the time remaining for the maths channel average operation to sample the input
before performing the calculation.
Period
For averaging functions, this allows a period to be entered, over which the value is to be
averaged. Selectable periods are: 0.125, 0.25, 0.5, 1, 2, 5, 10, 20, 30 seconds, 1, 2, 5, 10,
20, 30 minutes, 1, 2, 6, 12, 24 hours.
Note:
* Virtual channels 16 to 30 (supplied with Modbus Master and EtherNet/IP options only) come
without alarms
VirtualChan1
Math
Add
180.36 Units
Good
2
Units
Descriptor
Type
Operation
PV
Status
Resolution
Units
Virtual Channel.1.Main
Input1
Input2
93.49°C
86.8°C
A5E45696052A Rev-AA