
Chapter 4 ________________________________________________________________ Operation
VAISALA ______________________________________________________________________ 127
5. Select Invert relay 1... , press TEST. Now the selected relay
output is forced to opposite state. Press OK to return to normal
operation.
6. Press EXIT to return to the basic display.
RTEST
Use the serial line command RTEST [ON/OFF ON/OFF] to test the
operation of the relays.
Example: Testing all four relays.
>rtest on on on on
ON ON ON ON
>
>rtest off off off off
OFF OFF OFF OFF
Enter the command RTEST to stop testing.
Operation of the RS-485 Module
RS-485 interface enables communication between RS-485 network and
DMT340 transmitter. The RS-485 interface is isolated and offers a
maximum communications rate of 115 200 bits/s. (For maximum bus
length of 1 km, use bit rate 19200 b/s or less.)
When selecting an RS-232-RS-485 converters for the network, avoid self
powered converters as they don't necessarily support the needed power
consumption.
Echo function shall be always disabled (OFF) when using the 2-wire
connection. When using the 4-wire connection you can disable/enable the
echo setting.
NOTE
User port on DMT340 main board cannot be used and connected when
RS-485 module is connected. Service port is operating normally.
Networking Commands
Set the RS-422/485 interface by using the following commands. The
other serial line commands are presented in section List of Serial
Commands on page 94.
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