The CLICK PLUS series of controllers offers low-cost, brick/stackable CPU options with varying degrees of capability so you can choose the features that best fit your application. Built-in Wi-Fi and Bluetooth, serial ports, micro-SD for log data storage, Run-time edits, high-speed counter/timer inputs and PID Functions with Auto-tune are all available options with these low-cost CPUs.
Modbus RTU, Modbus TCP
The CLICK PLUS C2-01CPU PLC comes with built-in Ethernet; RS-232 serial port; micro-B USB port; Real Time Clock; Battery Backup Option; PID; Option Module Slot.
See attached spec. sheet.