Vaisala Drycap DMT152, User Manual

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5.3 Configuring Analog Outputs
DMT152 has two analog output channels. These channels can function either as normal
measurement channels, or produce an ON/OFF output if the measurement exceeds a given
alarm level (limit alarm) or if the measurement reading is frozen (for example, during sensor
purge).
• In the normal operation mode, a channel outputs voltage or current that corresponds to
the reading of the selected measurement parameter.
• In the ON/OFF output mode, a channel outputs a specified voltage or current level. This
mode is used by the limit alarm and the purge status alarm.
• In the LED alarm output mode, the channel outputs operation voltage for the LED cable.
The LED will light up to indicate a frozen measurement output which is typically caused
by transmitter start-up or sensor purge. The LED will blink at approximately 0.5 Hz if the
malfunction alarm is active. The LED will not light up for the limit alarm.
Additionally, DMT152 has a malfunction alarm that is always enabled in normal operation
mode. The malfunction alarm can also be enabled for a channel in ON/OFF output mode. See
Malfunction Alarm (page 38) .
When the transmitter is ordered from Vaisala, the modes are configured as specified in the
order form. You can change the operation settings after delivery using the
AMODE command:
Table 12 AMODE command
Syntax Description
AMODE [c1 c2] <cr> c1 = Channel 1 analog output mode. Available
options are:
1 0 … 20 mA
2 4 … 20 mA
4 0 … 5 V
5 0 … 10 V
7 I alarm (ON/OFF output using current)
8 U alarm (ON/OFF output using voltage)
Modes 1 … 5 are normal measurement modes,
where malfunction alarm is always enabled, and
limit alarm and purge status alarm are disabled.
c2 = Channel 2 analog output mode. Available
options are:
1 0 … 20 mA
2 4 … 20 mA
4 0 … 5 V
5 0 … 10 V
6 LED alarm
7 I alarm (ON/OFF output using current)
8 U alarm (ON/OFF output using voltage)
Enable mode 6 for channel 2 if you are using the
Vaisala LED cable.
Chapter 5 – Serial Line Operation
35