On our PoKeys57CNC USB and ETHERNET motion controller, we use IDC connectors for connection of STEP, DIR and EN signals to the stepper or servo driver. There is a good reason why we decided to use such connectors as stepper motor connector and why it is one of the best options.
What is IDC connector?
IDC (insulation displacement connector) is electrical connector, used in electronics, that doesn’t need the wire to be stripped before putting on a connector. It is used with ribbon cables for fast, reliable connections in various electronic devices.
The connector has sharp, metal “fingers” with precise gap between them. That enables the cable to displace and cut the plastic insulation and make a reliable electrical contact with the conductor in the cable. There are usually 6-30 conductors in a ribbon cable and all of them can be pressed onto the connector at once which makes it an ideal and fast connectivity option.
IDC connector assembly
For reliable connection when crimping an IDC connector it is important to follow some simple rules. The cable has to be cut strainght with insulation on the end of the cable intact. Then it is very important to align the cable properly in the connector so each conductors falls in only one metal blade.
Using IDC crimping tool press the connector together and check that the aligment is OK and that there is no damage on the connector. For extra safety you can also check the continuity with the multimeter to ensure that there are no shorts between the conductors. It is possible to also press the connector together without special pliers, but it is important to press it as parallel as possible in order to not break anything and ensure proper connection.
Shielding in IDC stepper motor connector
Big problem for step, direction and enable signals is also EMI interference. Usually, all the wires should be shielded with GND to prevent outside interference from disturbing the signal. But it is often quite cumbersome to connect the shielding to the ground without shorting it with nearby signal wires. The connectors are also harder to assemble and would not be suited for wiring the stepper motor connectors and signals to the control board.
That is why we decided to use another way of shielding the signal wires. There are 10 wires in our stepper motor connector and we designed the wiring to be in such a way, that every signal is placed between two ground wires. That way, interference that could disturb the signals is minimized and reliability of the system is improved.
Conclusion
There are several good reasons, why we use IDC connectors for our stepper motor drivers. To summarize them we can say that the IDC connector is beneficial because:
- easy and fast to crimp
- realiable and can be crimped with little errors
- with design we ensured shielding against EMI interference
- can be assembled in cables with various lengths
- fairly compact with regards to pin count
Please also check out our other blog posts.
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