Setpoints; Basic Terms - LEYBOLD GRAPHIX ONE Instruction Manual

7.2

Setpoints

In this parameter group, you may configure the switching functions. The GRAPHIX controller
is equipped with the following switching function parameters:

SP1-On to SP6-On

SP1-Off to SP6-Off
7.2.1

Basic Terms

Switching Functions
The GRAPHIX controller provides a total of six switching function relays, which may be freely
assigned to the three measurement channels maximum. The relays switch over depending
on the measured pressure. The contacts of the relays are floating and may be used through
the connection marked Relay Output for switching purposes
Output, page 28).
Threshold Values
The switching action of the individual relays is defined through two parameters in each case:
the lower threshold value and the upper threshold value of the switching function.
Lower Threshold Value SPx-On
The lower threshold value controls switching on of the related switching function. When the
pressure drops below the lower threshold value, the relay switches on. The common contact
of the relay is then connected to the normally open contact.
Upper Threshold Value SPx-Off
The upper threshold value controls switching off of the related switching function. When the
pressure exceeds the upper threshold value, the relay switches off. The common contact of
the relay is then connected to the normally closed contact.
Hysteresis
In the pressure range between the two threshold values, the current relay status is
maintained. Within this range, the relay will not switch over and the relay status will depend
on the previous switching function
The range between the lower and the upper threshold value produces a certain degree of
hysteresis between switching on and switching off of the relay. Hysteresis prevents rapid
cycling between on and off when the pressure is close to a switching threshold.
GA300550402_002_C1 – 10/2016
( Figure 72, page 75).
Figure 72 – Response of the switching function in
p
t
NO
COM
NC
( Chapter 5.3.5 Relay
case of pressure changes
Pressure]
Time
Normally open contact
Common contact
Normally closed contact
75