I have this cable connected to an inline tap, the control cabinet schematics calls this a "programming drop". Since this cable has a pre-assembled DB9 Male connector on the opposite end from the tap, I am wondering what pin goes to which wire. According to Schneider all drop cables used on an inline tap uses two sets of twisted pair cables. One set of wires is color-coded white and orange, the other set is white and blue. Each pair has a bare shield wire. I have an illustration of how the wires are connected in the tap, what I need to know is which pins are used in the DB9 connector. The connector has all 9 pins but all 9 could not possible be used.

 

The tap you're referring to is part number 990NAD23000. Inside the tap, one or two trunk leads and the drop cable are connected to punch-down terminals. If only one trunk cable is used, the opposite terminals are jumpered to a 120 ohm network termination resistor. The tap connects the orange and white pair to the blue and white conductors, respectively, of the left trunk cable and the blue and white pair to the blue and white conductors, respectively, of the right trunk cable. All of the grounds are connected together.

The DB9 connector uses pins 1, 2 and 3 in the standard Modbus Plus pinout, and must only be connected to a Modbus Plus port such as found on various Modicon PLCs, I/O adapters, network bridges and PC interfaces. Inside the connector, both white wires connect to pin 1, ground connects to pin 2 and orange and blue connect to pin 3. (I may have pins 1 and 3 reversed, since the diagram I have isn't explicit on that point.) This maintains the integrity of the Modbus Plus network, which does not allow single pair taps, which are permitted in some other networks such as Allen-Bradley Data Highway Plus.

For more info, search for document 31003525_k03_000_03.pdf, Modicon Modbus Plus Network Planning and Installation Guide. You may find it under the old (AEG Modicon era) number of 890 USE 100 00.

"Programming drop" sounds like something I put in a few projects with MB+ networks.

 

You only need 3 pins in DB9 connector (male or female), connect
Sh in pin 1, Orange and Blue in pin 2 and 2 white in pin 3.

That connection works perfectly, to communication a PC to MB+ netwok

 

> You only need 3 pins in DB9 connector (male or female), connect
> Sh in pin 1, Orange and Blue in pin 2 and 2 white in pin 3.

> That connection works perfectly, to communication a PC to MB+ network

is this also applicable to Quantum PLC?