- Lollette LE3U is a “copy” of the Mitsubishi FX3U PLC for $60 on AliExpress while the original costs around $1000.
- All configuration is done using Mitsubishi’s proprietary software GX Developer or GX Works2 which cost another $500 but have a 60-day free trial available online.
- It features 14 digital inputs, 6 analog inputs, 2 analog output and 10 relay outputs.
- The RS485 port is not configured by default so you can’t control any of the relays or read input values without first uploading new configuration program.
- Programming is done using visual Ladder language which is somewhat confusing to get started until you realise that it’s pretty much a mapping of input triggers, registers and their values.
- Each physical input maps to a register which can then change another output register depending on certain rules.
- Configuring parameters is “moving” 1-byte or 2-byte strings into registers.
Configure RS485 Modbus
To configure the device as a Modbus “slave”, hook into the
M8002 event and configure the following registers:
D8120with the details for the serial protocol. Set it to
H4081to enable Modbus RTU slave protocol with 8 data bits, 0 parity bits, 1 stop bit and a 9600bps transfer rate.
D8121for the device ID or station number. Set to
1is the device ID.
D8129for the communication timeout (optional). Set to
100is the timeout in milliseconds.
The 4-byte values are entered as a string of matching hex values starting from the lowest bit (please ignore the actual register values since this is from a different device):
See these two videos for detailed instructions: