The VersaMax Micro family from Emerson (formerly GE Fanuc) is a line of compact, DIN-rail-mountable PLCs designed for small machine control, pump skids, conveyor systems, and stand-alone process loops. Six base controller sizes — Micro 14, 20, 23, 28, 40, and 64 — span from 14 to 64 built-in I/O points, each expandable to up to 176 total points through four snap-on modules.

How do the six Micro models compare?

At the entry level, the Micro 14 provides 8 DC inputs and 6 outputs with a single RS-232 port, 9K words of logic memory, and super-capacitor-backed RAM — ideal for simple relay-replacement and timer/counter applications. The Micro 23 is the only model with built-in analog I/O (2 inputs + 1 output, 12-bit), adding a real-time clock, battery-backed RAM, and RS-485. The Micro 28 and 40 step up to 24K words of logic memory and add motion commands (Home, Jog, Ramp, Blended Move) with 100kHz high-speed counters and 65kHz PWM on the Micro 40. The Micro 64 (40DI/24DO) supports online program editing — the only Micro model with that capability — and offers an optional second port with Ethernet. The Micro 20 rounds out the middle with 12DI/8DO and motion commands.

What stays the same across the family?

All Micro controllers execute at approximately 1.0μs per Boolean instruction with a 1.1ms/K scan rate. All support PID control, floating-point math, subroutines, Modbus RTU master/slave, and SNP slave protocols. All accept up to four expansion units — discrete I/O, analog I/O, RTD/thermocouple, high-speed counter, and motion modules — and are programmed via Emerson's Machine Edition (VersaMax Pro) software. The compact footprint (roughly 150×90×76mm for base units) and DIN-rail mounting suit space-constrained control panels.