Connecting RS-485 serial line - OPT100

OPT100 Installation Guide

Document code
Document type
User guide
  • RS-485 cable
  • Screwdriver with 3-mm-wide (0.12‑in) slotted head
  • Cable stripping tool
Default settings of the RS-485 line are;
  • Baud rate: 19200
  • Transmission mode: 8E1
  • Modbus slave ID: 240
  1. Open the cable gland marked RS-485 on the DGA monitor. Remove the plug and store it for later use.
  2. Prepare the cable for connection:
    1. Measure how much cable you need to reach from the cable gland to terminal block Y1.
    2. Remove the outer sheath and cable braid from the part of the cable that will be left inside the DGA monitor.
    3. Strip the ends of the individual wires to expose the conductors for 1 cm (0.4 in).
    4. Remove some more of the outer sheath to expose more cable braid. This part of the braid should be connected to the cable gland.
  3. Insert the cable through the outer nut and the inner seal, and start inserting the cable through the cable gland. Stop when you reach the section of the cable where the metal braid is exposed.
  4. Arrange the cable braid so that it makes contact with the cable gland when it is closed. Push the inner seal in place and tighten the outer nut.
  5. Inside the DGA monitor, connect the wires to terminal block Y1:
    Verify the wiring colors of your cable before making any connections.
    Table 1. Terminal block Y1 wiring
    Signal Terminal
    RS-485 + 1
    RS-485 − 3
    Common 5
    Figure 1. Terminal block Y1 wiring example