Special Functions
11.4.3 Limit Value Responses
Relay Allocation
As standard, both limit values of all measuring points of a device are used for
fault alarms (s. 11.3.5), i.e. if an exceeding of a limit value occurs at any mea-
suring point, the relay 0 responds if an Alarm Relay Cable or a corresponding
Relay Adapter (s. man. 5.2/3) is used. It only opens again, after all measured
values have dropped below the limit values by as much as the hysteresis. If a
limit value has not been defined, the measuring range limit will be used as limit
value. A sensor breakage will always cause a fault alarm.
To distinguish between max value exceeding and min value undershooting the
alarm signal generators can be re-programmed to variant 1
(s. 11.6.2, man 6.10.9)
.
If it is necessary to selectively identify and evalu-
ate faults, the function
Action Max
,
Action
Min
or the assistant menu
LIMITS, ALARM
can be used to allocate individual relays to the
limit values. It is also possible to allocate several
limit values to one relay. For this purpose the re-
lay cables provide 2 relays (0 and 1) and the re-
lay adapter (ZA 8000-RTA) provides 4 relays (0
to 3). This mode also has to be set as variant 2
in the output module (s. 11.6.2, man. 6.10.9).
Output socket: A2
Setting the relay module to variant 2:
EA Trigger-Alarm
(relay int. allocated)
2: Rx int. allocated
Activating relay x at limit value exceeding Max:
7 Action max: -----
Rx
Activating relay y at limit value undershooting Min:
7 Action min: -----
Ry
Clearing the relay allocation using the key:
<CLR>
Starting and Stopping a Measurement
Exceeding of limit values can not only be used for fault alarms but also to start
or stop a measurement (s. man. 6.6.3). The start command or stop command
is assigned to a limit value - also by means of the functions
Action max
and
Action min
.
Start measuring operation at limit value, max.:
7 Aktion Max:
Start
--
S
Manual inquiry at limit value, maximum:
7 Aktion Max:
Manu
--
M
Zero-setting timer 2 at limit value, maximum:
7 Aktion Max:
TZero
--
T
Stop measuring operation at limit value, min:
7 Aktion Min:
Stop
--
E
Clear response by using the key:
<CLR>
Printout of relay assignment x (s. man 6.10.8) and action Y (s. man 6.6.3) as
assembled code in the sensor programming (s. man 6.10.1).
ALMEMO
®
2890-9
63
LIMITS, ALARM
±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±
Select measuring channel:
M0: 216.7 °C
7 Limit max: 300.0 °C
Relay: 0
7 Limit min: 100.0 °C
Relay: 1
Output socket: A2
Use alarm cable, set variant
EA Trigger-Alarm
2: Rx int. assigned
Relay: 01------
M PRINT ESC
