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Problems with FC5 (AG_SEND)

Created by: ADG124 at: 4/29/2010 4:24 PM (5 Replies)

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4/29/2010 4:24 PM	Rate (0)
ADG124 Posts: 3 Rating: (0)	Hi, 6 Months ago I completed a project with an S7-315 pn/dp and CP 343-1 which is obtaining / sending data to an S7-400 system via industrial Ethernet. Everything worked well until last week when I send them and upgrade to deal with an annoying bug in the program. They put the updated FC into the processor and reported that the communications stopped working, at which point they panicked and put the old program back. The problem I have is that the update I send them has nothing to do with the communications section of the program. Having spent the past couple of days trying to reproduce their results using PLCSIM I’ve come to the conclusion that the FC5 (AG_SEND) block must have hung. Can anybody tell me :- Does the block have a timeout? and How do I interrupt the transmission? I used the example in the Entry ID: 17853532 as the source for my comms program. Many thanks in advance Andy
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5/1/2010 6:36 PM	Rate (0)
smiffy Platinum Expert Joined: 1/17/2007 Last visit: 10/21/2024 Posts: 1547 Rating: (537)	What is the status code from the AG_SEND block?
	Programming today is the race between software engineers building bigger and better idiot proof programs, and the universe producing bigger and better idiots. So far, the universe is winning...
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5/4/2010 4:26 PM	Rate (0)
ADG124 Posts: 3 Rating: (0)	Hi It must have been 8181H since anything else would cause an error message to be generated on the display. Best regards Andy
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5/5/2010 2:53 PM	Rate (0)
smiffy Platinum Expert Joined: 1/17/2007 Last visit: 10/21/2024 Posts: 1547 Rating: (537)	ADG124 Does the block have a timeout? Not that I am am aware of. If you call it with ACT=1, it will continue to try and send the data. It will not start a new send job until the previous one has completed. If you want to get the status of the send job, then do the same call with ACT=0. ADG124 How do I interrupt the transmission? The only way I know to interrupt the transmission is to use the AG_CNTRL call with CMD = 03. But be aware this resets the whole connection. See section 10.5 and section 7.3.1 of the following manual for details of AG_CNTRL and AG_SEND respectively. Also be aware that not all CP's or firmwares support AG_CNTRL. Manual ADG124 It must have been 8181H since anything else would cause an error message to be generated on the display What display are you referring to? If the code is 8181H, this means that the send job is still is progress. How are you calling the block (which OB etc.)? Have you tried calling the block with ACT=1 on first call then with ACT=0 on susequent calls to get the lastest status of the send job. This is how I used it in the past and it has worked fine for me.
	Programming today is the race between software engineers building bigger and better idiot proof programs, and the universe producing bigger and better idiots. So far, the universe is winning...
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5/6/2010 11:09 AM	Rate (0)
ADG124 Posts: 3 Rating: (0)	smiffy What display are you referring to? Sorry, I should have told you I have an TP177B connected to the Profibus port of the CPU to supply operator instructions. The PLC changes the message on the screen to" communications fault" if the status of the FC5 block is anything other than 0 or 8181H. smiffy How are you calling the block (which OB etc.)? The FC5 block is being call in OB35 (100ms Cyclic Interrupt ). I set a bit when a transmission is required, this supplies the ACT of the block with 1 for a program cycle .The Done of the block resets the transmission required. Which I think is the same as you are suggesting. I use the fact that the transmission bit is high to prevent the rest of the program overwriting the transmission data. I have a fairly slow transmission rate of a maximum of 1 message every 2.5 seconds and part to part time of a minimum of 30 seconds (the actual time depends on the operator and the production mix of the plant) If the block hasn't completed its transmission will setting ACT=1 start a new transmission?
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5/6/2010 3:12 PM	Rate (0)
smiffy Platinum Expert Joined: 1/17/2007 Last visit: 10/21/2024 Posts: 1547 Rating: (537)	ADG124 The PLC changes the message on the screen to" communications fault" if the status of the FC5 block is anything other than 0 or 8181H. OK that should be fine. ADG124 The FC5 block is being call in OB35 (100ms Cyclic Interrupt ). I set a bit when a transmission is required, this supplies the ACT of the block with 1 for a program cycle .The Done of the block resets the transmission required. Which I think is the same as you are suggesting. I assume that you are feeding back the DONE output into a set / reset flipflop so that DONE resets the ACT input. ADG124 If the block hasn't completed its transmission will setting ACT=1 start a new transmission? Good question. It is not entirely clear from the manual if the transmission is active when ACT is set or on the rising edge of ACT. In my experience, I recall that the transmission is active whenever ACT is set, so calling AG_SEND cyclically with ACT=1 will continually keep restarting the send job and never get round to finishing it and updating the DONE/ERROR outputs. You should read section A-188 of the manual in the link in the previous post. For convenience I will include the salient details below:- Case a: Sequence with older CP types The send job is executed as soon as the parameter ACT = 1 is passed. Following this, the parameter ACT = 0 must be passed in at least one further call. The status code in the output parameters DONE, ERROR and STATUS is updated in each block call and can be evaluated. To update the status code without starting a new send job, start a new block call with the parameter ACT = 0. Case b: Sequence with newer CP types (S7-300 only!) The send job is started as soon as the parameter ACT = 1 is passed. In contrast to case a, the protocol used here to transfer the data segments (each 240 bytes of user data) requires the FC to be called again for each segment. Depending on the length of the user data, you must therefore continue to call the FC with ACT=0 until transfer of the entire data record is indicated; at least one call with ACT=0 is always necessary. The data is transferred to the communication partner in segments of 240 bytes. The status code in the output parameters DONE, ERROR and STATUS is updated in each block call and can be evaluated. So it would seem that you have to have a least one call with ACT=0 to get the updated status of the send job. The way I have used it in the past is to call AG_SEND with ACT=1 for one cycle only. I then call AG_SEND cyclically with ACT=0 to check the status of the send job until I see the DONE or ERROR outputs set. I then repeat the cycle to start another new transmission. This has always worked for me. I suggest you give it a try.
	Programming today is the race between software engineers building bigger and better idiot proof programs, and the universe producing bigger and better idiots. So far, the universe is winning...
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