Common Problems - BCPro - LIT-12011908 - General System Information - BCPro System - 4.0

MS/TP Communications Bus for the BCPro System Technical Bulletin

Product name
BCPro System
Document type
Technical Bulletin
Document number
Revision date

Several factors can influence the behavior of the MS/TP bus. In addition, certain problems can affect the bus in multiple ways and have more than one symptom, making the exact diagnosis difficult. For example, duplicate addresses on the bus can degrade performance, make a device go offline, or stop communication completely. Table 1 lists common problems that you should consider when troubleshooting an MS/TP bus. The first row, Multiple Symptoms, lists possible problem causes that can have multiple symptoms.

Table 1. Common Problems


Possible Causes

Multiple Symptoms

  • Excessive bus errors are occurring.
  • A device was added or changed with a duplicate address (may not be the same address as some devices having problems, and may have happened some time before the problem was noticed).
  • Wiring errors or wire problems exist.
  • The baud rate was changed on some devices on the network, but not all devices.
  • Max Master was changed incorrectly (this may have happened some time before the problem was noticed).
  • A download is in progress.
  • There is a fault at a device.
  • A repeater is needed or configured incorrectly.
  • There is a duplicated Device Object name or instance.
  • The EOL termination is improperly set.

Poor Performance

  • Excessive bus traffic exists (bus overload).
  • Baud rate may be set too low.
  • Too many devices may exist on the network.
  • Unaccounted devices are on the network (that is, not mapped to the BCPro Workstation).
  • Unusually slow devices are on the network or devices that are slow to pass the token.

Devices Go Offline

  • Device is failing to respond to the BCPro Workstation request.
  • Power or other failure occurred at the device.
  • Communication is disabled at the device.
  • Multiple integrations (Remote Field Bus integration or BACnet integration) are using the same BACnet Router.
  • More than one supervisory device is using the same BACnet Router.

Device Does Not Come Online

  • The device may be connected to the wrong bus.
  • The baud rate of a new device is incompatible with the baud rate of the running network.
  • No device on the network is configured to use a specific baud rate (normally the BACnet Router), but all devices are set to use auto baud. At least one device, typically the bus supervisor ( BACnet Router), must have an assigned baud rate. Set the baud rate in the bus supervisor and set all other devices to Auto baud.
  • Device failed to download Main Code.
  • Duplicate addresses exist