How fast bits are sent. Common Modbus values: 9600, 19200, 38400, 57600, 115200.
Tip: Start with the slave’s documented baud. Higher ≠ better if the line is long/noisy.
rtuBufferSize
rtuBufferSize:number
Driver/read buffer size. Modbus-RTU max response is ~256 bytes (253 PDU + addr + CRC). Give headroom.
Typical: 512 or 1024.
rtuDataBits
rtuDataBits:number
Bits per character, usually 8 for Modbus (a.k.a. “8N1” or “8E1”). Some very old gear uses 7.
Typical: 8.
parity?: 'none' | 'even' | 'mark' | 'odd' | 'space'
Error detection bit in each character. Modbus-RTU devices most often use even or none.
Typical: 'even' (8E1) or 'none' (8N1). Match the slave exactly.
rtuPath
rtuPath:string
rtuRtsCts
rtuRtsCts:boolean
Hardware flow control (RTS/CTS). RS-485 adapters often don’t use CTS/RTS for flow; many do auto-direction. Enable only if your adapter/slave requires it.
Typical: false for Modbus-RTU.
rtuStopBits
rtuStopBits:number
Time between characters to let receivers resync. Usually 1; some devices require 2 at high baud or with parity=none.
Typical: 1 (or 2 if the device manual says so).
rtuX
rtuX:boolean
rtuXany
rtuXany:boolean
rtuXoff
rtuXoff:boolean
rtuXon
rtuXon:boolean
Software (in-band) flow control. Modbus frames are binary and should not use XON/XOFF.
Typical: false for all three.
SHORT/USHORT: we read the first byte under the configured byte order. If your device actually uses the other byte.