4 Wiring with 800
4.7 Working with function blocks
130
Control Relay easy800
11/11 MN04902001Z-EN
www.eaton.com
Example: Timing relay function block
Assigning operands at the input of a function block
The following operands can be assigned to the input of a function block:
•
Constants, e.g.: 42,
•
Markers such as MD, MW, MB,
•
Analog output QA,
•
Analog inputs IA,
•
the QV outputs of all function blocks.
You can set the parameters of the function block as follows:
▶
Scroll with the
Í
or
Ú
cursor buttons through the constants of the
function block inputs.
▶
Change the values for a parameter set:
•
OK: Switch to Entry mode.
•
ú í
Change decimal place.
•
ÍÚ
Change value at a decimal place.
▶
OK: Save constant immediately and exit the parameter display by
pressing ESC.
ESC: Keep the previous setting and exit the parameter display.
Ensure that the input of a function block is not assigned impermissible values
during operation. There is a danger of this if you assign negative values to the
input although the function block can only accept positive values.
If, for example, the T timing relay function block is triggered with a negative
time setpoint, it will no longer switch in the expected way.
You should therefore take care to exclude such situations, as the easy800
device cannot foresee these when the parameters are assigned.
In most applications, a thorough simulation is enough to prevent any
impermissible values at the function block input.
T 01 ?X M:S +
>I1 20:30
>I2
QV> MD96
Function Block:
Timing relay
Switch function:
On-delayed with random time
Time range:
M:S (Minute:Second)
Set time >I1:
20 min 30 s
Actual time QV>:
Copied to MD96
￫
Tip: If, for example, you have set the output QV of the AR
arithmetic function block at input I1 of the T function block, you
should connect a CP comparator in between in order to signal
the occurrence of a negative value.
