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The Direction for 2005 and beyond: Ethernet |
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Ethernet is no longer an option for advanced, complicated Industrial Devices like Drives – ETHERNET IS A REQUIREMENT. Ethernet is the fastest growing segment of Industrial Networking for one reason – The Market (Your Customers) Loves Ethernet. The reasons for this are many and obvious: |
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- They’re very familiar and comfortable with Ethernet
- They have the components and expertise in house
- They believe it is a low cost networking option
- They love the additional benefits provided by web servers
- They want the fast 10/100 speed (even though they can’t explain why)
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Unfortunately there is no single Ethernet application layer for Drive System control. Users in some vertical markets have coalesced around a standard; other markets remain DCS or PLC vendor driven while others will change from job to job or plant to plant. What follows is a summary of the different types of Ethernet application layers available to drive manufacturers and integrators and the advantages and disadvantages of each. |
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TCP/IP |
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Quick Summary : TCP/IP is a protocol standard that comprises the two layers present in almost every Internet message. TCP is the Transport Control Protocol. It is the connection-based protocol that verifies that your message was received at the destination. TCP will retransmit messages that aren’t correctly received and report an error if the message can’t be delivered or if the connection is lost. IP is the Internet Protocol. The Internet Protocol routes messages, fragments large messages into multiple packets along with a number of other important tasks. Together, these protocols reliably move your data from a sending station to a receiving station. Unfortunately, the data is meaningless unless the two stations have a prior agreement on the format of the data. It’s like telling someone the score of the basketball game was 97 to 96. The data is received; it’s understood but worthless without a prior understanding of what teams played and who scored 97 and who scored 96. |
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Advantages: TCP/IP is provided in almost every RTOS (Real Time Operating System). There are well-understood programming instructions for creating TCP/IP connections and sending and receiving data over TCP/IP. In short, it’s available, low cost (free if it’s included in your OS) and reliable.
Disadvantages : TCP/IP alone provides no additional benefits to the end user. To use TCP/IP device manufacturers must implement some proprietary data protocol that end users must use to access the data in the drive. Drives only implementing TCP/IP are essentially mute as far as most Programmable Controllers are concerned. |
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