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AG RECEIVE

Created by: Jack123 at: 7/5/2008 12:14 PM (3 Replies)

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7/5/2008 12:14 PM	Rate (0)
Jack123 Posts: 3 Rating: (0)	Dear All, I have to communicate with a Atlas Copco PF 3000 controller which supports ethernet. I have CP-343-1 Lean module & at present & i used TCP connection. Requirement: I will send 21 bytes to the controller thru AG send & on send done bit i will disable this AG SEND. And the controller will respond to this by sending back me 63 byte data. On receiving the 63 byte data i will disable the AG RECEIVE. Like this i have to do multiple send receives as shown in the flow chart in this attached sheet. Now the problem is if an operation is performed in the controller then on its own the controller will send the datas (122 Bytes). On that time exactly i am unable to make enable the AG Receive block for data receive & the problem starts. So what i made is to enable AG send momentarily as on when requirement( as like previous logic) & AG receive i made continous enable. And i faced the problem i am not getting NDR output. So i made to compare the receive number of receive bytes & assumed in place of NDR output. But still AG RECEIVE hangs on saying error some times. Please help any body came across similar problem? Attachment logic.JPG (456 Downloads)
Jack123 Posts: 3 Rating: (0)
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7/7/2008 12:14 PM	Rate (1)
J_Bell Posts: 5822 Rating: (412)	Hello, I am sorry but this is not that easy with the TCP Connections. The Issue with the CP’s is that the CP does not recognize the End of a Datagram received. Therefore you have to open a receive buffer that is exactly the size of the Telegram you expect. Now we get into trouble, because you mention that you ma receive Telegrams of two different sizes. Now we have different ways to solve this situation. The best would be if the Data has some kind of Header that identifies the Telegram you are about to receive, that way you can divide the Receive into two parts. 1. You receive the Header to decide how much Data you will receive besides the Header, do not worry, the Data that is left of the Telegram is kept in the ring buffer of the CP. 2. Youreceive it with the second AG_RECEIVE Call the data left in the buffer of the CP. This way you have to chance to handle different sizes of send telegrams. If you have no chance to identify the type of telegram you may try to poll Data byte wise... and if you run into a timeout you can restart the AG_RECEIVE again. I hopeI could help you a step forward. Best regards J_Bell
J_Bell Posts: 5822 Rating: (412)
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7/7/2008 5:31 PM	Rate (0)
Jack123 Posts: 3 Rating: (0)	Dear Mr.Bell, Thanks a lot....... My problem is solved from your 1st suggestion itself. U did a great job from remote....... Thanks & Well done.
Jack123 Posts: 3 Rating: (0)
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7/8/2008 9:36 AM	Rate (0)
J_Bell Posts: 5822 Rating: (412)	Dear Jack123, it is great to hear that it works now. Well done... J_Bell
J_Bell Posts: 5822 Rating: (412)
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