EAGLEHAWK CONTROLLER – INSTALLATION & COMMISSIONING INSTRUCTIONS
27
EN1Z-1005GE51
R0216
EFFECT OF POLL RATE + SUBSCRIBED POINTS ON CPU LOAD
The poll rate set for the EAGLEHAWK and the chosen number of subscribed points both make a demand on the CPU load. The
EAGLEHAWK has been verified to support the following scenario.
SUPERVISOR (20 points via FOX)
APPLICATION:
1 AHU WITH
CentraLine APPLICATION
TRENDING:
14 POINTS
ALARMING:
10 POINTS
GRAPHICS:
1 PX PAGE, 38 POINTS
Panel Bus
34 POINTS
Modbus
4 POINTS
Fig. 46. Example application
In this scenario, the EAGLEHAWK is controlling 6 AHU plants which are using CentraLine Macros.
In this scenario, the following is assumed:
▪
Each EAGLEHAWK is connected to one Mixed I/O Panel Bus module (with 34 points), with a normal poll rate (10s);
▪
There are 4 Modbus points, with a normal poll rate (5s);
▪
10 Panel Bus and 4 Modbus points are in trend;
▪
1 PX graphic with 38 points;
▪
10
alarm
extensions;
▪
20 points have been exported to Niagara Supervisor;
▪
All points on the Supervisor are subscribed;
▪
All Modbus points are subscribed;
▪
One graphic is visible on the screen.
The following table provides information on the effect of the number of subscribed points and the poll rate upon the CPU load. In
all cases, it is assumed that the given bus is without control logic, alarming, or trending, and that it is the only bus running at the
EAGLEHAWK.
Table 20. Effects of poll rate and no. of subscribed points on CPU load
bus
no. of subscribed points
poll rate
value change-time
CPU load (approx.)
Panel Bus
400
10 sec (normal)
N/A
52%
Panel Bus
400
1 sec (fast)
N/A
71%
BACnet MS/TP
400
10 sec (normal)
N/A
60%
BACnet MS/TP
200
COV
20 sec
58%
C-Bus 100
COV
15
sec
29%
NOTE:
The CPU load should never exceed 80% on a continuous basis. The default load (with an empty station) is approx.
15%.