Hi, Charles!
You should check the plugs again.

The 60124 has a 7-pin plug and the 60125 has four 7-pin sockets on the sides and a 9-pin socket on the opposite side. So it seems you plug the 7-pin plug into a 9-pin socket.
The 60124 should fit on either side of the 60125 where it has two sockets.

My 60124 has this plastic centre pin.
Maybe you have a 60126 cable (79"), not a 60124 cable (about 5").

Charles,

Marklins statement is correct but incomplete.

If for example you have a CS2 with a number of 60125(terminals) and/or 60126(extension cables) running down your layout and DO want to put your slave CS2 at the FAR end then , yes, you do need to plug the 60123(Slave adapter cable) into the end of the last 60125.

If , however , you want your 2 (or more) CS2s side by side then the above answer would mean that you have to loop the end of the chain back to your main operational area.

The solution in this case is to plug the 2 x CS2s together with the 60123 and then commence your string of extension cables and terminals
e.g. CS2<9f> <9m>--60123--<6m> <6f>CS2<9f> <9m>--60125(optional)<9f> <9m>----60126(optional)-----<9f> <9m>--60125(optional)<9f>

This does not preclude you adding a 3rd CS2 (with a 60123 adapter cable) to EITHER ..
... the left of the first unit
... the end of the last 60125
... in the middle of the chain (but it cannot be out the side 7 pin sockets of the 60125, it must use the 9 pin socket)

Note: if any of the Slave CS2 are in the middle of the chain they must be powered on for the devices "past" it to work.

To some extend.

The CAN bus has to be terminated. The side ports of the 60125 are terminated and only allow for end devices with short cables. There are no extension cables for the MS2 as the cables after the termination must not be too long.

Same principle for ESU. They make it easier by using standard network cables, but termination must be observed.

Some may know termination from SCSI devices. Two or three devices will work even with incorrect termination - add a fourth device and you get sporadic failures.

Back to topic:
The 60126 cable has 9 pins, the plug of the MS2 has 10 pins, the 60124 adapter goes from 10 pins to 7 pins. You can connect an MS2 with the 60124 adapter to any side port of the 60125.
The 60126 cables can be used to move the 60125 terminal closer to the MS2. This ensures you have a properly terminated CAN bus.
Extending the MS2 cable with the 60126 (9 pin vs. 10 pin) could lead to CAN bus problems (communication errors between any devices, not just between MS2 and the rest).

Sorry Charles - I just can't help myself. I know where you can put the long cable.

Regards
Greg

I thought it was not possible to connect more than 2 Ecos together... .
( at the beginning it was even not possible to connect another Ecos... only the sniffer could work with its proper limitations..then an upgrade came to allow 2 Ecos out of the sniffer... )