...
By default, the terminator on the board of VT336 and VT336PoE is always ON. The cap is inserted between the two contacts providing 120R resistance. The terminator is a J16 connector on the board.
...
Sensors are connected in a daisy chain connection.
120Ω resistor is used at the end of the chain which is equal to the resistance of the cable.
A twisted pair cable is used for A(+) and B(-).
"VT336 and VT336PoE / DIN monitoring units" have an internal termination and by default, it is switched to ON position. (If required possible to switch OFF)
Up to 32 devices can be used.
Overall cable length is no more than 1000 meters.
...
Switch off the Vutlan monitoring unit.
Open the enclosure’s bottom and pull the mainboard from the enclosure.
Find a Modbus jumper and take the cap off.
Put everything back together.
...
You can use a range of Sensors/Meters/Devices for Modbus.Developer notes: