What this M258 controller brings to a panel
The TM258LF42DRS0 is a Modicon M258 programmable logic controller with 42 discrete I/O points — 26 inputs (10 fast, 12 regular, 4 regular-input) and 16 outputs (4 fast transistor, 12 relay). That mix suits a machine with a mix of high-speed sensors and general-purpose valve or contactor loads, all on a single backplane. It runs on a 20.4...28.8 V DC supply (24 V nominal) and draws 17.22 W at full load — a figure to budget into the enclosure thermal calculation, especially if the panel is sealed or stacked with other heat sources. The controller mounts on a symmetrical DIN rail and measures 262.5 mm wide by 99 mm tall by 85 mm deep — a footprint that fits a standard 300 mm wide sub-panel with room for a terminal block row alongside.
High-speed inputs and CANopen bus — what they mean for machine control
Eight counting inputs run at 200 kHz, which is enough for incremental encoder feedback on a servo axis or high-speed flowmeter pulse trains. The fast inputs (10 total) have a configurable anti-bounce filter from 2 µs to 4 ms, so you can tune out contact chatter on a limit switch without losing encoder edges. The CANopen port supports baud rates from 10 kbit/s (5000 m bus length) up to 1 Mbit/s (4 m bus length). For a typical machine cell with drives and I/O blocks within 100 m, 500 kbit/s is the practical sweet spot — fast enough for cycle-time coordination, long enough to reach the far end of the line. Onboard Ethernet provides network status and activity LEDs, plus a USB host port for program download or data logging to a thumb drive — no special programming cable needed for field updates.
Memory, clock, and data retention — the real-world limits
Flash memory is 128 MB, internal RAM is 64 MB. That is enough for a mid-size application with HMI screens, recipe tables, and a few hundred rungs of ladder or structured text. The real-time clock drifts less than 30 s/month without user calibration, and under 6 s/month with calibration — adequate for time-stamped alarms and production logs that don't need NTP-grade precision. Retain and persistent variables are backed by a CR2477M Renata lithium cell rated for 1.5 years. That backup time covers a long plant shutdown or a power outage over a holiday break, but the battery is user-replaceable — factor a replacement into the PM schedule every 18 months if the controller is often unpowered.
Compliance and production status
The TM258LF42DRS0 carries CE marking and is certified to UL 508, CSA C22.2 No 142, CSA C22.2 No 213, and IEC 61131-2. That covers North American and European panel builds without a separate approval chase.