Limit alarm, Serial communication, Connecting to serial interface – Vaisala MMT162 User Manual

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User's Guide ______________________________________________________________________

22 __________________________________________________________________ M210934EN-C

Limit Alarm

The limit alarm is activated when the measured parameter 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.

Serial Communication

Connecting to Serial Interface

The MMT162 can be connected to a PC using the RS-485 line,

for example using the USB serial connection cable (Vaisala item

219690). The cable also provides operation power to the transmitter from

the USB port. It is OK to connect the USB serial connection cable even if

the transmitter is already supplied with operation power from another

cable.

To connect to serial interface:

If you have not used the MMT162 USB serial connection cable

before, install the driver that came with the cable. Refer to section

instructions.

Connect the USB serial connection cable between your PC and the

RS-485 port of the MMT162 (port II).

Open the terminal program (for example, PuTTY in Microsoft

Windows

Set the serial settings of the terminal program, and open the

connection. See the following table.