Correcting physical Communication Bus problems - Verasys - LC-BYP200-0 - LC-ZEC310-0 - Field Device - BYP200 - ZEC310

The Communication Bus is subject to a number of physical factors that can affect performance. Consider the following list of common physical problems that affect the Communications Bus:

• Check the status LED to verify power at the controller.
• Check wires
  • Verify that the wire is a 0.6 mm (22 AWG) three-conductor, twisted, shielded cable.
  • Verify that the shield is continuous and hard-grounded at one end.
• Check wiring
  • Check for and eliminate T-Taps, wire configurations that create a T shape, and star configurations.
  • Ensure that the bus is wired in a daisy-chain fashion.
  • Verify that appropriate devices have three wires entering and exiting each terminal. Devices at the ends of the trunk do not have this wiring.
• Check EOL switch settings
  • Verify that only the EOL switch at the end of the system bus is set to ON, and all other system bus EOL switches are set to OFF.
• Check connections, polarity, and lengths
  • Verify that communications loops are less than approximately 304 m (1,000 ft) total in length.
  • If you are using one transformer to power multiple devices, verify that the device 24 VAC power connection follows the polarity of the common and 24 V terminations.
• Check for opens and shorts
• Check terminations
• Check addresses
  • Check for duplicate addresses.
  • Verify that the address range is sequential.
• Check for sources of interference
• Check bus voltages:
  • (+) to COM must be within 2.0 VDC to 3.0 VDC
  • (-) to COM must be within 1.5 VDC to 2.54 VDC
  • (+) to (-) must be within 0.3 VDC to 1.0 VDC