Modular electronics benches, digital and converter trainers, PLC brands that match the machinery local industry actually runs, and the compressed air and bench power that decide whether an automation laboratory works in year two.
An automation laboratory is the easiest engineering laboratory to buy badly, because everything in the catalogue looks like it teaches the same thing. A modular electronics bench, a PLC trainer and a flexible manufacturing cell are all described as hands-on. They serve completely different points in a student's education, and buying them in the wrong order leaves a department with a manufacturing cell nobody can program and a room full of students who have never wired a relay.
For a polytechnic diploma holder in Bangladesh, that is usually: read a wiring diagram, wire and test a motor starter circuit, fault-find a sensor, download and modify a ladder program, and work safely around a three-phase supply. For a university graduate it adds design: choose a sensor, condition its signal, size an amplifier, and write control logic that behaves when an input fails.
Those two lists produce different equipment. The diploma list is served by modules, panels, real industrial components and repetition. The degree list needs measurement, adjustable circuits and enough instrumentation for a student to see what a filter or an amplifier is actually doing. Most institutions need both, and the useful sequence is fundamentals, then digital, then control, then integration. Departments that buy a manufacturing cell first because it is impressive on a visit day discover that only two staff can operate it.
A breadboard, a handful of components and a multimeter will teach circuit theory to a motivated student for very little money. It will also lose components, produce intermittent faults that are the breadboard's rather than the circuit's, and consume the demonstrator's entire session on debugging contact resistance. That is the trade-off, and it is worth being blunt about it.
Modular systems solve the reliability problem and cost more. An integrated bench such as the LIEBA gives a base unit with plug-in boards, and the board set is what defines the syllabus coverage: N-M1 for direct current circuits, N-M2 for alternating current, N-M16 for electric networks, N-M17 for electromagnetism, N-M18 for three-phase, N-M3 and N-M4 for semiconductors, N-M5 for power supplies, N-M6 for oscillators, N-M7 for operational amplifiers, N-M8 for filters and N-M14 for optoelectronics. A general analogue circuits unit such as the M99 covers similar ground in a single board.
The practical guidance is to buy modules for the topics where a fault would waste the session, and breadboards for the topics where making the mistake is the lesson. Filters, oscillators and operational amplifiers belong on modules. Simple resistive networks and first transistor circuits are better on a breadboard, where a student can get it wrong and see why.
Whatever you choose, count the instruments. One oscilloscope shared between eight groups is the bottleneck that turns a three hour laboratory into forty minutes of measurement and two hours of waiting. Bench instruments are cheaper than trainers and they are the item most often under-ordered.
The digital half is usually well served and shallowly taught. Combinational and sequential logic modules (N-M11, N-M12, N-M13) cover the standard syllabus. What departments skip is the boundary between the analogue and digital worlds, which is where graduates actually work: analogue to digital and digital to analogue conversion (N-M10, N-M60, N-M61, or a dedicated unit such as the CADDA), and digital signal processing (a teaching unit such as the TDS).
If a budget forces a choice, the converter experiments are the higher value purchase. Sampling, quantisation and aliasing are the concepts students most reliably misunderstand, and they are almost impossible to teach convincingly on a whiteboard. A student who has watched a signal alias on a scope does not forget it.
This is the single most consequential specification decision in the laboratory, and it is not a technical one. A PLC trainer teaches the same logic whichever processor is inside it. What differs is the programming environment, the addressing convention and the name on the certificate the student can put on a CV.
In Bangladesh, the machinery a graduate meets is concentrated. Garment factory machinery, packaging lines, boilers and water treatment plants in the pharmaceutical and food sectors, cement and steel plant equipment: these are dominated by a small number of makers, with Siemens and Mitsubishi very widely represented and Omron, Allen Bradley, Panasonic and Delta appearing on specific imported equipment. Training a class exclusively on a brand that no local plant runs is training them for an interview they will not get.
Trainer families exist for each of these: AE-PLC-SIE for Siemens, AE-PLC-MIT for Mitsubishi, AE-PLC-AB for Allen Bradley, AE-PLC-OMR for Omron and AE-PLC-PAN for Panasonic. The sensible pattern for a department is a majority of stations on the dominant local brand and two stations on a second brand, so students learn that the concepts transfer and the syntax does not. Buying one of each of five brands teaches nobody anything well.
Two further points that are easy to miss at tender stage. First, software licensing: confirm how many seats are included, whether the licence is perpetual or annual, and whether the version runs on the operating system your computer laboratory actually has. Second, ask what the trainer connects to. A PLC wired only to lamps and switches teaches ladder syntax. A PLC wired to real sensors and actuators, as in a sorting workstation (AE-PLC-CF), a process control workstation (AE-PLC-CP), an industrial processes control workstation (AE-PLC-CPI), an elevator control application (AE-PLC-SE) or a sensor study system such as the BS-PLC, teaches fault-finding, which is the employable skill.
A modular manufacturing system, built from stations such as a part feeder (AE-PLC-APS), a linear transport line (AE-PLC-T), a pneumatic handling station (AE-PLC-MAN), a quality control station (AE-PLC-VS), an RFID identification station (AE-PLC-RFID) and a storage station (AE-PLC-AL), is the most visible equipment a department can own and the hardest to keep running. The complete systems (AE-PLC-FMS1, FMS2, FMS5, FMS15) are collections of these stations working as a line.
Be honest about what it is for. A manufacturing cell is not a good way to teach a first PLC course, because the failure surface is too large for a beginner. It is an excellent final year and project platform, an excellent demonstration for industry visitors, and an excellent way to teach station-to-station communication and sequencing. Buy stations incrementally so that each one is usable alone, and only join them into a line once the department has a technician who can maintain the whole thing.
The supporting purchases matter more than the stations. Pneumatic and electro-pneumatic application trainers (AE-NS), hydraulic and electro-hydraulic trainers (AE-HD) and a vacuum technology unit (AE-V) teach the actuation side that a cell assumes students already know.
Three utilities decide the fate of an automation laboratory in Bangladesh, and none of them appear on the equipment list.
Add two small things that cost almost nothing and pay back constantly: an antistatic mat and wrist strap at the digital bench, and a lockable cupboard for the patch leads. Patch leads are the consumable of an electronics laboratory. Order twice as many as the trainers came with, in the same colours, and count them at the end of every session.
Finally, size the room to the assessment. If the practical examination requires each student individually to wire a circuit or download a program, the number of identical stations is set by the examination rather than by the teaching, because a board of examiners will not accept an exam run over three days with the questions leaking between sittings.