plz help me about can bus....

[dani]

Hi all,

I want to interface a sensor that supports Fieldbus,Profibus and Modebus with Pic Microcontroller for measurments. Now as i am just started study the possiblites to accomplish this task i have a dought in my mind.

The question is ..

Is it possible to use can bus feature of PIC18F458 for fieldbus,profibus,or modebus implementation.

Any ideas then plz plz guide me towards correct direction.

Regards

 

[Kaleem]

It is possible to interface CAN with other buses but that is not simple. I don't think that you can use the CAN feature of PIC as it to interface with profibus etc.

 

[dani]

HI Kaleeem,

Thanks for ur reply,

Tell me then what should i do to interface a sensor which gives out put in digital format which is based on one of the protocols i mentioned

i.e
HART,Fieldbus,ModeBus,Profibus

I want to use PIC microcontroller for this purpose, do any one have ideas..?

:?::?:

 

[baskan]

Hi dani,

Fieldbus is a general name for CANbus, Profibus etc.

1-You can use CAN feature of PIC and interface to your sensor if your sensor has any CAN interface protocol such as DeviceNet or CANOpen.It is quite easy.So which CAN protocol your sensor is using?

2-You can use Modbus which is a protocol on RS232 or RS485 signal levels.
To use modbus, you should write a modbus interface into your PIC. There are lots of free C code available via google for modbus protocol. You may need some chips like max485, if your sensor supports only rs485.

3-Profibus is also RS485 based (simens)protocol with speeds upto 12Mbits. And I suspect if you can properly interface with profibus of your sensor.

4-The HART protocol uses 1200 baud Frequency Shift Keying (FSK).It uses the same wires of 4-20ma. So it needs filtering and additional(beyond my) knowledge.

To summerize.
Either use modbus(uart of PIC).
OR use CANbus(CAN of PIC)