Endress+Hauser Fieldgate FXA520, Operating Instructions Manual

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6 Configuring the Fieldgate Fieldgate FXA520
68 Hauser
6.4.4 Description/Range/Limit/Alarm
Depending on device type, up to four measured values can be configured within the Web server.
The significance of the parameters is described in Tables 6-9 and 6-10.
Limit values
Four limit values can be configured in the Web server. Fieldgate tracks the status changes "LIMIT"
- the measured value moves out of limit and "RESET" - the measured value moves back into limit.
Table 6-9 indicates when the status changes "LIMIT" and "RESET" occur. The Fieldgate can be
configured to send a limit alarm e-mail on either or both conditions, see Chapter 5.6.1
Table 6-9: Alarm status table for e-mail messaging
Hysteresis
The hysteresis function allows a band to be placed below the HI or HI HI limit or above the LO or
LO LO limit which delays the status change to RESET after a a limit has been violated. This is used
to stop the limits from triggering for example, when the surface of the liquid in the tank is turbulent.
Fig. 6-2 shows the effect for a hysteresis of 5% on a HI limit of 80% and a low limit of 15%
Fig. 6-2: Example of level limits and hysteresis
to LL to L to OK to H to HH
from LL
– RESET RESET* LIMIT LIMIT
from L
LIMIT – RESET LIMIT LIMIT
from OK
LIMIT LIMIT – LIMIT LIMIT
from H
LIMIT LIMIT RESET – LIMIT
from HH
LIMIT LIMIT RESET* RESET –
*RESET made only if H/L not used or change to OK occurs within 1 cycle
Level %
75
Hysteresis
80
t
t
HI limit
15
20
LO limit
Hysteresis
Alarm status
HI alarm “1”
HI alarm “0”
LO alarm “1”
LO alarm “0”
limit
reset
limit
reset