Multimeter checks of the BAS port (system bus port) - Verasys - LC-VZC100-0 - LC-VZCPNL-0 - Field Device - VZC100 - VZCPNL

Verasys Zone Coordinator (VZC) Installation Guide

Brand
Verasys
Product name
VZC100
VZCPNL
Document type
Installation Guide
Part number
24-10143-1280
Document revision
C
Revision date
2021-10-14
Language
English

About this task

If the zone coordinator board is connected to a BAS bus (system bus), but the BS BUS LED is off steady, then the zone coordinator board is not receiving communications on the BAS bus. To diagnose the problem, use a DC voltmeter and complete the following steps:

Procedure

  1. Remove the BAS plug from the BAS port J12 system bus port (BS port).
    Note: Take note of the position of the BAS EOL switch S2 to return it to its correct position after taking the measurement. The correct position is one of the following two options:
    • If the zone coordinator is not the EOL device, ensure that the EOL switch is set to off.
    • If zone coordinator is the EOL device, ensure that the EOL switch is set to ON.
  2. Switch the BAS EOL switch S2 to the ON position during the measurement, otherwise the voltage readings are out of the given range.
  3. Measure the voltage between the + and pins on the BAS bus terminal block by placing the positive lead of the voltmeter on the + pin and the negative lead of the voltmeter on the pin.
  4. Observe the voltage reading. The voltage reading can be in the range of 0.38 VDC to 0.47 VDC. The readings show the following possible circumstances:
    • If functioning correctly, the reading is steady and varies by no more than one or two millivolts.
    • A reading within the range of 0.38 VDC to 0.47 VDC indicates that the BAS transceiver on the zone coordinator board is not damaged.
    • If the reading is outside the range of 0.38 VDC to 0.47 VDC by a large amount, the transceiver or its associated circuitry might be damaged.
  5. If the reading in is within the range of 0.38 VDC to 0.47 VDC and the BAS transceiver is not damaged, return switch S2 (BAS EOL) to its correct position and reconnect the BAS terminal block plug into the BAS terminal block J12 on the zone coordinator board.
  6. Take a second voltage reading on the BAS plug between the + and wire connections. If there are still no communications, assess if one of the following circumstances is occurring:
    • If the voltage reading is steady but out of the 0.38 VDC to 0.47 VDC range, then the issue could be improper EOL terminations, wiring, or some other issue.
    • If you connect the BAS bus to a third-party BAS, the reading can be outside of the usual range. In this instance, acceptable voltage readings are between 0.25 VDC to 0.5 VDC.
    • If communications are occurring on the BAS bus, then the voltage measured fluctuate generally in the range of 0.1 VDC to 0.5 VDC if the bus is properly terminated.
      Note: The voltage readings may vary somewhat out of this range depending on bus loading and the type of voltmeter used. If the voltage readings fluctuate in the approximate range of 1.5 VDC to 3.5 VDC then it is likely there is no EOL termination set on the bus and you must set the EOL termination at the EOL device.
    Note: You can also use the meter checks detailed for the BAS port for the CS port (zone bus).