Beckhoff / KL Bus Terminals

KL terminals use K-bus and EL terminals use E-bus. They look almost identical on the rail, they will not work in each other's stations, and the coupler at the left-hand end is what tells you which you have.

KL is the earlier Beckhoff I/O range, predating the EtherCAT EL terminals. Still running plenty of New Zealand machines that have never needed replacing.

Check the coupler before ordering terminals

The first thing to establish, and it takes one look at the rail.

A BK coupler at the head of the rail means KL terminals. An EK coupler means EL terminals.

The terminals themselves are similar in size and appearance, and the numbering follows the same logic, so it is an easy mistake to make from a parts list alone.

Send us a photo of the rail including the leftmost device and we will confirm it.

The numbering matches the EL range

Helpfully, Beckhoff kept the same scheme, so if you can read one you can read the other.

So a KL3054 and an EL3054 are the same function on different buses. Four-channel analogue inputs, and not interchangeable.

That parallel is convenient for identifying what a terminal does, and it is exactly why the two ranges get confused.

A K-bus station needs an end terminal too

Same requirement as EtherCAT, different part.

The end terminal is not optional and costs very little. If a station has been extended and nobody refitted it, that is worth checking before chasing a communication fault.

The BK couplers

The coupler is chosen by the fieldbus the station sits on, and they are not interchangeable.

The BK1120 is the bridge worth knowing about

Genuinely useful on a migration.

A BK1120 connects K-bus terminals to an EtherCAT network. So an existing rail of KL terminals can be brought onto EtherCAT without replacing the I/O.

That turns a full I/O replacement into a coupler swap. The field wiring stays, the terminals stay, and the station appears on the EtherCAT network.

If a plant is moving to EtherCAT and has racks of KL terminals, that is the question to ask before quoting a rebuild.

BC and BX are controllers, not couplers

A distinction that matters when replacing one.

A BK is a coupler. It passes I/O to a master elsewhere.

A BC or BX is a bus controller. It has its own programmable logic and can run a program locally.

So replacing a BC with a BK removes the logic from the station. If the machine has no separate PLC, that station is running it.

Check what the head of the rail actually is.

KL is discontinued, and that is the opportunity

Beckhoff has moved to EtherCAT, so the KL range is mature to discontinued depending on the terminal.

The first option is what we are set up for. A KL terminal of the same number goes back in and works, because like the EL range it carries no user configuration.

Secondary supply of KL thins out over time and does not improve. If a machine has years left in it, buy the spares while they exist.

Terminals carry no configuration

The same good news as the EtherCAT range.

A KL terminal is addressed by its position on the rail, and the station is described in the controller. There are no settings in the terminal.

So a shelf KL terminal is a working KL terminal. That makes spares holding straightforward on a discontinued platform, which is unusual.

And if several terminals came off during a rebuild, they go back in the same order.

K-bus power

As with E-bus, the coupler supplies the terminals with bus current, and power feed terminals extend the budget where a long station needs more.

The symptom of running short is the same and equally misleading: terminals toward the far end behave erratically or fail to be recognised, which looks like a faulty terminal.

If a station has been extended and the last few terminals are misbehaving, that is worth checking before ordering a replacement.

The K-bus prefixes

KS is to KL what ES is to EL: the same function with pluggable field wiring, so the wiring stays in the connector when the terminal comes out.

What to send us

The full terminal number. Function and channel count are in it.

The coupler at the head of the rail. BK means K-bus, EK means E-bus.

Whether the head device is a coupler or a controller. BK against BC or BX.

Whether you need the end terminal.

A photo of the whole rail. Beckhoff labels the front clearly and one photo usually identifies every terminal on the station.

What we can supply

KL Bus Terminals across the digital, analogue, position and communication ranges.

BK couplers for Ethernet, PROFIBUS, CANopen, DeviceNet and the BK1120 EtherCAT bridge.

BC and BX controllers.

KL9010 end terminals, power feed terminals and accessories.

KL is discontinued in large part, so this is new old stock, surplus and tested used.

We buy Beckhoff KL

KL Bus Terminals hold real value to the machines still running them, because a like-for-like terminal goes in with no configuration and no rewiring.

If you are migrating a plant to EtherCAT, do not scrap the KL terminals. They are worth considerably more to another plant than as scrap, and the couplers more so. See Sell To Us.

Related

Beckhoff overview, EtherCAT Terminals and CX embedded PCs.

For legacy distributed I/O from other brands see Siemens ET 200M, Allen-Bradley FLEX and POINT I/O, Modicon Momentum and ABB S800.

Send us your part numbers

Check the coupler first. A BK at the head of the rail means KL terminals, and an EK means EL. 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 Beckhoff Automation. Beckhoff, TwinCAT and EtherCAT are trademarks of Beckhoff Automation. All trademarks, brand names and part numbers are the property of their respective owners and are used here for identification purposes only.