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My Micro-step drive and PLC need a simple resistor network between their i/o ports.The optocouplers in the stepper drive have a max input current of 15mA, while the controller needs to output at least 20mA to give valid signals. The circuit below satisfies these requirements.

schematic

simulate this circuit – Schematic created using CircuitLab

What is a good way to mount these resistors in my PLC cabinet?

Are there terminal blocks that accommodate through hole resistors nicely, or would panel/chassis mount resistors be a better solution?

I have looked at some of the terminal blocks out there, but I haven't seen an elegant solution for adding through hole components. I have looked at panel mount resistors as well, but the power ratings are often much greater than I need.

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  • \$\begingroup\$ Are you sure that the PLC MUST output 20 mA, or is it just capable of outputing 20 mA? If the latter is true, then you just need a suitable series resistor to limit input current to the optocoupler. \$\endgroup\$ Commented Jan 20, 2019 at 16:32
  • \$\begingroup\$ Agreed. Give us a link and a page reference for the output specification. \$\endgroup\$
    – Transistor
    Commented Jan 20, 2019 at 20:19
  • \$\begingroup\$ Check out my previous post. It is a question about the same system regarding exactly what you both are interested in. \$\endgroup\$
    – seabiscuit
    Commented Jan 21, 2019 at 1:55
  • \$\begingroup\$ Something like this works too. digikey.com/en/products/detail/phoenix-contact/2775249/2552972 \$\endgroup\$ Commented Feb 7, 2020 at 17:12

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A search for "DIN rail component carrier" throws up images such as this.

enter image description here

Figure 1. A user-configurable PCB with screw terminals and DIN rail mount. Image source: Google image search.

For just one or two resistors or diodes it's common to connect them using standard DIN terminals.

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  • \$\begingroup\$ This looks really great! \$\endgroup\$
    – seabiscuit
    Commented Jan 20, 2019 at 16:09
  • \$\begingroup\$ I recommend that you un-accept my answer for a day or two to encourage other contributions. You'll get all sorts of ideas from them and maybe a better solution than this. Thanks. \$\endgroup\$
    – Transistor
    Commented Jan 20, 2019 at 16:21
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I know this is an old question, but I found a couple more options for this while looking for something similar:

I found this from one supplier, haven't found anyone else that makes them.

Ocean Controls 2 x 2K2 Resistor module

2 resistor module from Ocean Controls

As mentioned above, the various big terminal block manufacturers have options for soldering in components - for example, these are all from Phoenix Contact: enter image description here

Those are PTME 6-BE, UDK 4-DUR, PTTB 2,5-2BE

Phoenix also sell a solderless component holder that uses a spring clamp system to hold & connect through-hole components:

enter image description here

This replaces the blade in a disconnect terminal block - so you need 3 bits - the resistor, the component holder (P-CO), and a disconnect terminal block (e.g. ST 2,5-TG)

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