string host = "modbus-device.local";
int port = 502;

using var client = new ModbusClient(host, port);
await client.Connect();

byte deviceIdentifier = 5;
ushort startAddress = 19000;
ushort count = 2;

var registers = await client.ReadHoldingRegisters(deviceIdentifier, startAddress, count);
float voltage = registers.GetSingle();

Console.WriteLine($"The voltage between L1 and N is: {voltage:N2}V");