User's Guide ______________________________________________________________________
22 __________________________________________________________________ M210934EN-B
Normal Operation Mode and Malfunction
Alarm
In the normal operation mode, a channel outputs voltage or current that
corresponds to the reading of the selected quantity.
If the transmitter is malfunctioning, the channel output is set to a pre-
defined level. This level can be changed using the
AERR
command; see
NOTE
The malfunction alarm overrides the limit alarm mode. If the
transmitter is malfunctioning, the analog outputs are always set to the
levels specified with the
AERR
command.
Limit Alarm
The limit alarm is activated when the measured quantity goes below the
low limit, or above the high limit. The alarm levels and limits are
configurable using the
ALARM
command (see page 35). By default, the
alarm levels are set as follows:
- For
current output
, an active alarm is indicated by the current being
at the maximum of the scale (20 mA).
- For
voltage output
, an active alarm is indicated by the voltage being
at the maximum of the selected scale. For example, if the voltage
output scale is 0 … 5 V, an output of 5 V indicates the alarm is active.
- For
LED alarm,
an active alarm is indicated by a lit LED. When the
alarm status is low, the LED is not lit. If the transmitter is
malfunctioning or it cannot measure for some reason, this causes the
LED to blink at 0.5 Hz frequency.
LED alarm indicator is integrated to a LED cable (Vaisala item
MP300LEDCBL) that can be ordered and used instead of a regular
connection cable.
