Schneider / Twido

A compact Twido has non-removable screw terminals and a modular one has removable connectors. That single difference decides whether replacing a controller means unwiring every terminal.

Twido is the discontinued Schneider small PLC range, superseded by Modicon M221 and M241. Still running small machines and plant across New Zealand.

Compact or modular decides the replacement job

Start here, because it is the practical difference.

On a compact controller every field wire comes off individually and goes back on. On a modular one the connector unplugs.

That is worth knowing when quoting downtime rather than just parts. A compact Twido swap is an hour of careful work and a chance to get a wire wrong; a modular one is minutes.

Reading a Twido part number

Take TWDLCAE40DRF.

Two single letters that change everything

The fourth character is Ethernet.

And the output letter is sink or source.

T and U are one letter apart and are opposite. Same trap as Omron DT and DT1 and ABB DI810 and DI814. Fit the wrong one and no output works.

The base unit range

The RTC is embedded on the 40 I/O compacts

Worth noting. The 40 I/O compact controllers have an embedded real time clock. The 24 I/O ones do not, and use a cartridge instead.

So if an application does anything time-based on a 24 I/O Twido, there is a cartridge in the slot.

One slot, and you have to choose

The constraint that surprises people.

Schneider specifies the slot use as memory cartridge or realtime clock cartridge.

One slot, two possible cartridges, and you cannot have both.

So on a 24 I/O compact, an application needing both extra memory and a clock cannot be done on that base. That is a real limitation and it explains some otherwise odd hardware choices on older machines.

The memory cartridges

The 64 kB cartridge does not fit a compact controller, and it does more than the 32 kB one. It extends the available memory rather than only backing up.

The cartridge is also how a program moves between controllers, which on a discontinued platform is genuinely useful. A cartridge from a failed unit will load the application into a replacement.

So when a Twido fails, keep the cartridge.

The battery is not supplied

Direct from the Schneider hardware guide, and it stops jobs.

The external battery must be provided by the user. No external battery is included with the Twido controller's package.

Data backup on internal RAM is 30 days with the lithium backup, and the published figures also cover a much shorter period without it.

So a new Twido arriving on site has no battery. If retained data matters, order one with the controller.

The first two inputs are different

A detail that matters if an application uses fast counting.

The first two inputs draw more current and have lower impedance, because they are the fast inputs used for counting and event capture.

So if a machine uses an encoder or a high speed count, those signals are on I0.0 and I0.1 and cannot simply be moved to a spare input.

Inputs are sink or source

Helpfully, Twido input signals can be both sink and source. The inputs are flexible even though the transistor outputs are not.

Specifications

Four expansion modules is the ceiling. If a machine has grown past that, no amount of module ordering fixes it and the base has to change.

PID on a small PLC is worth knowing about. A Twido can close a temperature or pressure loop without a separate controller, and on an older machine that may be exactly what it is doing.

Software

Both are discontinued alongside the hardware. Same position as PL7 and Concept covered elsewhere on this site: the tools run on old Windows versions and licences are scarce.

Which makes the memory cartridge the practical answer. If you can transfer the program by cartridge, you never need to open it.

Twido is discontinued. What now?

The M221 is the successor, and it is a different platform rather than a drop-in. Different terminals, different software, different footprint.

On a machine with years left in it, a used Twido of the same reference is very often the cheaper and faster answer, particularly on a compact base where the alternative involves rewiring.

Secondary supply of Twido thins out over time. If you run several, one spare base of each type you have is a sensible holding.

What to send us

The full reference. Every character carries something: compact or modular, supply, Ethernet, I/O count, output type, terminal type.

Whether you have the memory cartridge.

Whether you need a battery. One is not supplied.

What expansion modules are fitted.

Whether the application uses the fast inputs, PID or event processing.

What we can supply

Base controllers. Compact and modular across the range, in AC and DC supply and relay and transistor output versions.

Expansion modules. Discrete and analogue I/O, AS-Interface and CANopen.

Cartridges and accessories. 32 kB and 64 kB memory cartridges, RTC cartridges, batteries, serial adaptors and programming cables.

Twido is discontinued, so this is new old stock, surplus and tested used.

We buy Twido

Twido holds value to the machines still running it, and the cartridges and programming cables are worth keeping with the controllers. If you are migrating, do not scrap them. See Sell To Us.

Related

Schneider overview. Modicon M340 and M580 and Zelio smart relays, which cover the range above and below Twido.

For small PLCs from other brands see Siemens S7-1200, Allen-Bradley MicroLogix and Omron CP1.

Send us your references

Check whether yours is a compact or a modular base, because that decides whether a replacement means rewiring. And keep the cartridge. Quotes in NZD including GST.

Request a quote

Industech is an independent supplier of new, surplus and used industrial automation equipment. We are not an authorised distributor of, approved by, sanctioned by, or affiliated with Schneider Electric. Schneider Electric, Twido, TwidoSoft, TwidoSuite and Modicon are trademarks of Schneider Electric. All trademarks, brand names and references are the property of their respective owners and are used here for identification purposes only.