Cbus Clock and unit address duplicated

For the last few days, I am having a problem with our client cbus network. When we arrived here, the switches don't seem to work though there is voltage running across the network).
It does sound strange, but my finding is if the clock is active (assume) on the current equipment (relays, dimmers etc), the network will not work. So what I did, I plugged my vers 4 PCI, and make sure the clock is active, then only I am able to open the network. If I disable the PCI clock, the network will not work anymore and the funny thing is the older switches (white 4gang key input sometimes can toggle the lights but not the Neo+DLT switch. The DLT+ Neo will only work if PCI clock is active).
And the second issue is, if I scan the network, It will prompt me with duplicate unit. Though I believe this shouldn't happen, out of curiosity, unravel the network, then rescan, same message will appear. This is is very
strange indeed.
I am also attaching the Cbus event logs and hopefully this could assist in fault finding.

regards
Shah

 

All the symptoms you describe are indicative of a network having fairly fundamental communication problems. I suggest you work your way through all the basic checks of the network.

From page 24 of the C-Bus Training Manual Vol 1:
The following are important considerations when planning a C-Bus network:

• The maximum total length of Cat-5 UTP cables on any one C-Bus network is 1 km.
• The maximum recommended number of C-Bus units on any one network is 100 units. The actual number is dependent on the impedance and amount of flowing current. The current must not exceed 2A.
• Multiple C-Bus power supplies can be connected to a C-Bus network to provide sufficient power for C-Bus units. The power supplies will share the load evenly. The maximum combined power supply output for a single network is 2A. Examples of acceptable configurations for a single network are:

• 6 ? 5100PS rated at 350mA each
• 10 ? DIN Rail Output Unit on-board power supplies rated at 200mA each
• 30 ? Pro Series Dimmer power supplies (except the 12 Channel) rated at 60mA each.
• Any combination of power supply units is allowed as long as the total power available does not exceed 2A.

​

• Where more than 1 km of cable or 100 standard C-Bus units are required, two or more networks can be linked using a network bridge.
• Each C-Bus network requires only one network burden. A burden is contained within:

• all C-Bus output units (such as dimmers and relays)
• most system support devices (such as a PC or network interface)
• some input units (including C-Touch and the Four Channel General Input Unit).
• A network burden can also be assembled using a 1kW, 0.6W (or higher) resistor and a 10mF, 50V capacitor in series, connected across the C-Bus 36V rails.

​

• Each C-Bus network requires at least one (and a recommended maximum of three) system clock generating units. A system clock generator is contained within:

• all C-Bus output units (such as dimmers and relays)
• most system support devices (such as a PC or network interface)
• some input units (including C-Touch and the Four Channel General Input Unit).

​

• The maximum number of networks that may be combined in a single installation is 255.
• The maximum number of networks that may be connected in series to the local network is seven (using six network bridges).
• C-Bus power supply units (including DIN and Pro units) may be connected to different phases.
• Individual relay channels may be connected to different phases. On DIN Rail Dimmers, the 240V supply connected to the units? power supply and the output channels, must be on the same phase.
• The isolation between the 240Va.c. mains and the 36Vd.c. C-Bus circuitry is greater than 3.5kV. This is achieved using double wound transformers and opto-isolators.

 

CBus Traffic Analyser

Just to update on the report, I set the traffic analyser to scan for cbus messages and this is the result. It looks like too many messages are being transmitted. Could it be any of the hardware faulty??

Shah

 

Just a simple reply:

I will get the incorrect unravel messages if there is problem with my Burden! Sometime the software burden is deactivated after some strange situations...anyway, to make things simple, make sure you activate the clock and install a hardware burden, then you can do all your testing and identify faulty input units, which is the common issue with old type of switches.

 

I did suspected it at first, but after retrieving, the burden is still activate on the equipment status tab.

 

Something is really hammering your C-Bus network with messages. The C-Bus Traffic Report shows a sustained rate of around 40 messages per second, which is about as fast as C-Bus will go.

It isn't clear from the report which unit is generating these messages, or what type of messages they are. Can you tell from the log which unit these messages are coming from?

The error rate averages 0.7 errors per second, which is quite a lot too. It is possible that a lot of the messages you are seeing are due to re-tries following failed messages.

 

Are you referring to Cbus Toolkit log or the one in the diag utility?? Maybe tomorrow I will fire up the diag utility and see what sort of messages shown on it. I swear I couldn't see anything transmitted, neither the toolkit nor in the dev kit but I might miss that.
Any suggestion on troubleshooting this problem is highly appreciated.

Rgds
Shah

 

Diagnostic Utility is easiest, as all of the information we need is in there.

If you haven't already done so, check everything suggested by Newman. There do appear to be comms problems and these have to be addressed.

The next step is to find where these messages are coming from. You may find that much of the traffic disappears once the comms problems are fixed.

 

Problem Solved

Thanks guys,

I have managed to bring CBus back to 'Life'. Apparently there are a couple of issues. A very old faulty 4gang key input. And one of CBus Cat5 pairs has dropped below than 20Vdc. I am not sure whether the second problem should effect much on the system but just to be on the safe side, I have changed to a different pair. Thanks again.

Rgds
Shah