can-bus vs proffi-bus

Check out these 2 sites

http://www.canbus.us/

http://www.profibus.com/

EdK.

The two busses are similar in use as long as you are referring to Profibus DP. It's a bit confusing with naming. There are 3 Profi networks. Profibus DP is a sensor level network similar to CAN, DeviceNet or ASi. Profibus PA is a higher level network more like ControlNet and connects instrumentation like flow meters and such. Then there is Profinet which is Ethernet based like Modbus TCP or Ethernet/IP.

All busses can be affected by power surges and if you are having problems in that area you should consider putting the power supply on a UPS. The choice of bus is primarily determined by the equipment you are communicating with. Not all vendors support all busses. You may be limited to one or two choices if your chosen controller (PLC or DCS) and equipment (solenoid manifolds, prox switches etc.) have a limited overlap. The wiring and comm cards are different as well. Although you may be able to change from CAN to DeviceNet and keep the wiring, they are electrically identical and only differ in the protocol.

as you said only differ in protocol.

what is that and how it works

please inform me

The protocol is the specific messaging structure. For example, Modbus/TCP and Ethernet/IP are both able to connect up to the same ethernet network, but the top layer of the network which defines the message structure are different. This means that an Allen-Bradley PLC and a Modicon PLC can share the same network switch yet not be able to understand each other. They need a protocol converter in between to translate. DeviceNet and CAN are like that. The number of conductors and type of wire may be similar and the voltages are the same, but the message structures are different. You would need a translator in the middle. This adds complexity and cost, so you typically use the bus that is common to both the controller and device.

I hope that helps.

we have ups for can-bus. but still its failing. is it because of battery back-up problem. if yes what can i do? or is there any another problem.

I'm sorry, this is going beyond my capabilities. If you are still losing the network configuration and you are sure it is during a power event, then maybe the UPS is bad. If the batteries are older than 3 years and it is hot in the cabinet where the UPS is located you can try replacing the batteries. You can check all connections as well. But you might have a bad piece of equipment on the network. Even though the network has a UPS, maybe something else on the network like a VFD is not acting properly during a power event.

yes you are right. the pannel is comletely closed and there is no air ciculation. which is causing excess temperature in the pannel.

Well, that would do it.

We cannot see the extent of the problem.

Is it one device on bus? Two...? Most?

If it is one, try replace with spare. If no spare, swap with another of same type on bus - if the fault moves, device problem.

Your device settings might be held...

1. So long as device is powered.
2. So long as battery in device lasts.
3. In a programmable memory which does not forget with no power.

Any of them can fail.