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so for my question i have been asked this:
1.Explain the terms “Bus” and “Star” as applied to a modern programmable controller system.
2. Describe, with the aid of diagrams, a network configuration that could be using to connect a programmable controller system. To do this task, select one PLC network configuration that is commercially used on a typical PLC distributed system.
3. For the network configuration chosen in task b above, describe the protocols and communication standard used, include in your answer an outline of the advantages and disadvantages of this network.
Guidance: For 4c try to link the selected network to internationally recognised protocols and standards. 4a should be applied to PLCs and not computers
So I've no problem with question 1 however question 2 has got me in a pickle. So I have been told that DeviceNet is a network configuration however, in my study material that I've got it says its a network protocol. If it was only question 1-2 I'd of put DeviceNet down and gone in to detail about it however, due to question 3 this gives me pause because this wants me to go in to detail on a protocol. I'm pretty confident both questions would want me to do the same thing so I'm confused. I don't relay know what to put for question 2 because of what question 3 wants of me. I've put this for Q2-3 but i think it may only cover question 3:
One of the network configurations that can be used for a PLC is DeviceNet this is part of CANbus. This system links the PLC to all of the I/O as shown in the picture on the right: the DeviceNet scanner will link up to the PLC. This system is used because it can significantly reduce cabling costs and complexity. This is because rather than having to connect the PLC to each of the I/O individually it T’s off the main cable used. This system uses a 4-wire bus system which can support up to 62 devices on the same network.
Advantages: easy to set up, cheap, low maintenance costs with easy trouble shooting and highly reliable
Disadvantages: not very good for complex messages due to limited message size, limited bandwidth and the maximum cable length
ModBus is part of DeviceNet. Modbus is an open, serial communication protocol based on a master slave architecture; the PLC will be the master the devices slaves. The master (PLC) will send data to the slaves (I/O) these I/O will activate the commanded and wont send any data back to the PLC. If the PLC needs data from the I/O it will have to poll the slave and wait for a response; the master has to initiate the communication for this to happen. This means that if something was to go wrong with the I/O when it was told to do something the PLC will have to ask for that data to know if something did go wrong.
The communication standard used is IEC61158.
Could anyone help me understand what i need to do or let me know if I've indeed done what's required off me?
Thanks!
1.Explain the terms “Bus” and “Star” as applied to a modern programmable controller system.
2. Describe, with the aid of diagrams, a network configuration that could be using to connect a programmable controller system. To do this task, select one PLC network configuration that is commercially used on a typical PLC distributed system.
3. For the network configuration chosen in task b above, describe the protocols and communication standard used, include in your answer an outline of the advantages and disadvantages of this network.
Guidance: For 4c try to link the selected network to internationally recognised protocols and standards. 4a should be applied to PLCs and not computers
So I've no problem with question 1 however question 2 has got me in a pickle. So I have been told that DeviceNet is a network configuration however, in my study material that I've got it says its a network protocol. If it was only question 1-2 I'd of put DeviceNet down and gone in to detail about it however, due to question 3 this gives me pause because this wants me to go in to detail on a protocol. I'm pretty confident both questions would want me to do the same thing so I'm confused. I don't relay know what to put for question 2 because of what question 3 wants of me. I've put this for Q2-3 but i think it may only cover question 3:
One of the network configurations that can be used for a PLC is DeviceNet this is part of CANbus. This system links the PLC to all of the I/O as shown in the picture on the right: the DeviceNet scanner will link up to the PLC. This system is used because it can significantly reduce cabling costs and complexity. This is because rather than having to connect the PLC to each of the I/O individually it T’s off the main cable used. This system uses a 4-wire bus system which can support up to 62 devices on the same network.
Advantages: easy to set up, cheap, low maintenance costs with easy trouble shooting and highly reliable
Disadvantages: not very good for complex messages due to limited message size, limited bandwidth and the maximum cable length
ModBus is part of DeviceNet. Modbus is an open, serial communication protocol based on a master slave architecture; the PLC will be the master the devices slaves. The master (PLC) will send data to the slaves (I/O) these I/O will activate the commanded and wont send any data back to the PLC. If the PLC needs data from the I/O it will have to poll the slave and wait for a response; the master has to initiate the communication for this to happen. This means that if something was to go wrong with the I/O when it was told to do something the PLC will have to ask for that data to know if something did go wrong.
The communication standard used is IEC61158.
Could anyone help me understand what i need to do or let me know if I've indeed done what's required off me?
Thanks!
