PLC and HMI All-in-One Controller

A PLC and HMI all-in-one controller puts the programmable logic controller and the operator touch screen into one panel unit. On a small or medium machine this removes a component from the cabinet, the wiring between the two, and a second panel cut-out, which is the reason the format exists rather than being a packaging preference.

The units on this page cover screen sizes of 4.3, 7 and 10 inches, with cut-outs from 120×94 mm to 260×202 mm. Discrete I/O runs from 8 inputs and 8 outputs up to 24 inputs and 22 outputs by model. Analogue input and output, two PT100 channels, high-speed counting to 200 kHz and two 100 kHz pulse outputs are carried on the models that specify them, so the configuration is decided by what the machine has to do rather than by what the housing can hold.

Two instruction-set families are offered. The H series is compatible with 3U instructions and the HS series with 200 instructions. They are separate families, so a program written for one does not move to the other unchanged.

How a PLC and HMI all-in-one controller works

The logic part of the unit reads its inputs, runs the stored program, and writes its outputs in a repeating scan. What makes the scan dependable in a machine is not its speed but the isolation on the way in and out: every I/O point on these units is opto-isolated, so a transient picked up on a sensor cable does not reach the processor as a change of state. Inputs accept a positive or a negative trigger, which is what allows a sinking or a sourcing sensor to be connected without an interface.

The screen is not a display bolted to the front. It reads and writes the same registers the program uses, so a setpoint entered on the screen is the value the logic acts on, with no separate link to configure. Temperature from a PT100 reaches the program through the same arrangement, which is what allows a temperature loop to be closed inside the unit without a separate transmitter and a separate analogue input.

Relay outputs are the part that decides how much can be switched. Each point carries a maximum current and each common terminal carries a maximum for the group it feeds, and both apply at once: four points at their individual limit reach the limit of the common. Inductive loads draw a surge on break, which is why they are normally switched through an interposing relay rather than directly.

How to select the right unit

Begin with the screen. The size is set partly by how much has to be legible at once and partly by the cut-out the enclosure already has; a cut-out cannot be enlarged without remaking the panel, so it is usually the fixed constraint. The cut-out dimensions for this series are listed above and they differ enough between the sizes to be worth checking before choosing.

Then count the I/O. Discrete inputs and outputs are chosen by model, so the count is what selects the part rather than an expansion module. Where the machine needs analogue signals, or a PT100 directly, that narrows the choice further, because those channels are carried only on the models that list them.

Then decide on counting and communication. Encoders and positioning axis determine whether high-speed counting and pulse output are needed. For communication, the unit offers Ethernet, USB, RS-485 and RS-232 by model, with 4G or Wi-Fi on the models marked for it, and the two instruction-set families are separate, so an existing program is the constraint that decides which family is chosen.

State the screen size, the I/O count, whether analogue or PT100 is needed, whether counting is needed and what the unit has to talk to, and the model follows.

Limitations and points to confirm

This unit is a controller and an operator interface. It is not a safety device: none of the published figures describe a safety-rated input, a dual-channel architecture or a diagnostic coverage level, so an emergency stop, a guard interlock or a light curtain has to be implemented with dedicated safety hardware rather than through the program. The EMC figures quoted here are immunity levels, not a statement about functional safety.

Two parts of the supplied material are incomplete and are published as such rather than filled in. The HS series is named, but its model table is not included, so the individual codes for that family are not listed. And the protocols are given as a list alongside the ports without stating which protocol runs on which port; on a machine that has to join an existing network, that mapping should be confirmed before the order rather than at commissioning.

Several figures a specification often calls for are absent from the document and appear here as information required: program capacity, power-fail retention time, ingress protection, operating temperature and dielectric strength. The relay capacity is published as stated, at a maximum current per point and per common, and is not a load rating for an inductive load.

Before ordering, note that the meaning of the model suffixes is not defined in the supplied material. Where a particular suffix is wanted for a particular reason, ask for it by name and describe the behaviour needed, so the two can be matched rather than assumed.