Connector / Cabling Thoughts and Ideas

[Visitor]

I am working with a manufacturer of factory-built modular homes who wants to install a variety of sensors as each module is built. These sensors are wired back to a central panel in the module, or to a panel in an adjacent module. Sensor types include temperature, smoke, leak detectors, keypad access control, remote control of air conditioners and other things.

As we consider revising the circuit board, we'd like it to be more "plug and play". The original circuit board I designed uses 4mm pitch Weidmuller push terminal blocks. Push the tab, insert the wire. These work ok, but it's difficult for a factory guy to make all the connections to the current terminal blocks. I had considered 5mm pitch pluggable terminal blocks but there's not enough real estate to use them. 3.5mm terminal blocks are so small they're difficult to use.

I would like to install some type of connectors, so installation becomes a task of plugging cables into the right jack instead of dealing with individual wires.

RJ11, RJ14, RJ25 and RJ45 connectors are a possibility, but the jacks take up a lot of room on a circuit board.

I'm trying to come up with some different ideas. Ideally, a cable could be pre-built and run during construction, which means the connector has to be somewhat durable. The connector should also be field replaceable, to allow replacing a damaged connector or so that unterminated cables could be run. This only makes sense if installing the connector is easier than connecting wires to terminal blocks.

All of the connections are low voltage and low current and 24 or 28 gauge wire should be fine. 2 - 4 conductors are required depending on sensor type, and the maximum cable length is on the order of 30 meters. Most of the signals are not too picky about cable type. The cable should have conductors inside an overall jacket for protection – CAT5 cable is used for most of the connections currently.

This seems like an impossible ask but have you got any ideas besides modular connectors?

Thanks.

 

[KeepItSimpleStupid]

I don;t like the modular connectors at all because this sounds more like a fire alarm system. The cables are generally PTFE insulated, colored red and solid. They generally need to support some sort of contact monitoring. 4-20 mA sensors could definitely do that. Then you have approvals.

I did have to interface a work-built gas selection/shutdown panel by me to the fire alarm. Two gas detectors set off the fire alarm at the high level. Those two gas alarms and the fire alarm provided contacts for my system. I eventually used LED contact monitoring for fire, hydrogen and Hydrides. the LEDS were located in the gas selection/shutdown panel in the lab where the gasses were used.

The inputs were contact closures, wired as FORM C. Velocity detectors were part of the panel, but again no monitoring for wire break of the analog signals.

The Form C, LED method would detect if a cable was severed, but not just the NO contact wire. the main reasons for implementing it was distance, to know when the fire panel (FAP) was reset and to know when the FAP was disconnected. It was disconnected at my panel sometimes during testing and cleaning of the smoke detectors.

 

[rjenkinsgb]

How about discrete-wire IDC header strips?
There are various makes that fit 0.1" or 0.15" etc. pitch pin headers, with either endways or sideways cable entry.
They are also cheap!

Examples - cable socket:

3-643814-4 | TE Connectivity 4-Way IDC Connector Socket for Cable Mount, 1-Row | RS

uk.rs-online.com

PCB Headers:

640456-4 | TE Connectivity MTA-100 Series Straight Through Hole Pin Header, 4 Contact(s), 2.54mm Pitch, 1 Row(s), Unshrouded | RS

uk.rs-online.com

You do need a special crimp tool to fit them, the one we have is a pistol-style thing that moves along a pin in the connector each time its operated - you just put an unstripped wire in the tool slot and pull the trigger to make each pin connection.

We only used a single size/series, but the crimper head is swappable on the tool body for different types.

This is similar to ours but for side-entry rather than top-entry connectors.

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