Limit alarm - DMT152

DMT152 User Guide
Document code
M210865EN
Revision
K
Language
English
Product
DMT152
Document type
User guide

The limit alarm is activated when the measured parameter goes below the low limit or above the high limit. The alarm can be specified during ordering for a specified parameter, or configured on the serial line using the ALARM command.

When ordering a limit alarm, 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.
Using the ALARM command, you can also set a hysteresis value to prevent the repeated triggering of the alarm when the measurement fluctuates around a limit value.
Table 1. ALARM command
Syntax Description
ALARM ?<cr> View the current alarm settings.
ALARM<cr> Select at the prompt (?) whether the alarm is enabled or disabled and define the alarm limits.

The following example shows that a high limit alarm has been enabled for channel 1. If the measured value rises above the -40.00 °C Td limit, analog channel 1 is set to 5 V (Limit Hi = -40.00, Level Hi = 5.00). The malfunction alarm (aerr) is disabled for both channels.

Note that the term quantity in the serial interface corresponds to measurement parameter.

alarm ?
Channel 1:
Low Limit      :      OFF
High Limit     :       ON
Aerr           :      OFF
Quantity       :      Tdf
Limit Lo       :     0.00
Limit Hi       :   -40.00
Hysteresis     :     0.00
Level Lo       :     0.00
Level Hi       :     5.00
Channel 2:
Low Limit      :      OFF
High Limit     :      OFF
Aerr           :      OFF
Quantity       :      ppm
Limit Lo       :     0.00
Limit Hi       :     0.00
Hysteresis     :     0.00
Level Lo       :     0.00
Level Hi       :     0.00
Avoid enabling more than one alarm type for a channel.