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S7 300 master-slave profibus connection

Created by: xev2008 at: 11/2/2010 12:11 PM (8 Replies)

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11/2/2010 12:11 PM	Rate (0)
xev2008 Member Joined: 2/12/2009 Last visit: 9/3/2025 Posts: 5 Rating: (0)	Hello, It is possible to know, for a slave profibus, if it is connected to the master?? By any status bits? Cumps,

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11/2/2010 12:17 PM	Rate (0)
umencho Grandmaster Joined: 3/21/2006 Last visit: 1/10/2026 Posts: 10247 Rating: (1183)	Hello, Yes, it is possible. Look at http://support.automation.siemens.com/WW/view/en/19268381 BR, Hristo Mihalev

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11/2/2010 1:01 PM	Rate (0)
hdhosseini Diamond Member Joined: 1/28/2009 Last visit: 1/5/2026 Posts: 6892 Rating: (1368)	Hi please check these simple set of codes. [code] CALL SFC51 "RDSYSST" REQ :=#IN0 SZL_ID :=W#16#292 INDEX :=W#16#1 RET_VAL :=#TEMP3 BUSY :=#TEMP31 SZL_HEADER:=#TEMP4 DR :=#TEMP32 JBI M004 //failure of SFC51 processing BEU M004: NOP 0 //READ CONTENT OF DATA RECORD AN #TEMP32.TEMP34 //ZERO SHOWS FAULT = DB16.DBX 4.7 //1ST SLAVE FAILING AN #TEMP32.TEMP35 = DB16.DBX 5.0 //2ND SLAVE FAILING AN #TEMP32.TEMP36 = DB16.DBX 5.1 //3RD SLAVE FAILING AN #TEMP32.TEMP37 = DB16.DBX 5.2 //4TH SLAVE FAILING[/code] Best regards hdhosseini
	Demo Channel on Youtube
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11/2/2010 2:13 PM	Rate (0)
xev2008 Member Joined: 2/12/2009 Last visit: 9/3/2025 Posts: 5 Rating: (0)	Hello, Thankx for your answers, but i dont need to detect the faulty slaves. "Iam a slave" and i need to detect if there is a connection established to a master... Thanx!

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11/2/2010 2:32 PM	Rate (0)
hdhosseini Diamond Member Joined: 1/28/2009 Last visit: 1/5/2026 Posts: 6892 Rating: (1368)	Hello This solution is applicable to a master S7400 and an intelligent slave Such as an S7 300 station. Send a bit from master to slave via PROFIBUS connection,The bit should be a symmetrical pulse with fix duration. In slaveprogram check this bit as the life bit of your connection, when the bit is offfor more than normal time value, It may means you have lost your connection to master have trouble generating the pulse.(use CPU's clock memory)If your slave is a regular (compact or modular) ,This all done via PROFIBUS telegrams. Best regards hdhosseini
	Last edited by: hdhosseini at: 11/2/2010 2:35 PM Demo Channel on Youtube
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11/2/2010 3:18 PM	Rate (0)
xev2008 Member Joined: 2/12/2009 Last visit: 9/3/2025 Posts: 5 Rating: (0)	Hello, That is a good idea, but i dont have the master profibus code. I have several DP slaves and i need to check if they are connected or not to the master. I was expecting something like a status bit indicating that the conection with the master has been done. If the PLC detect it (there is a led indicating that), it means that internally this is a know status. I need that to my application. Thanx

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11/2/2010 3:50 PM	Rate (1)
hdhosseini Diamond Member Joined: 1/28/2009 Last visit: 1/5/2026 Posts: 6892 Rating: (1368)	Hi xev2008 1st, check this link for monitoring a CPU's LED.You think when you unplug a PROFIBUS in other slaves, your intelligent slave may return this by BF or SF.So monitor the LEDs. 2nd, I insist on my previous proposal,your master should be located in vicinity of you slaves.So take a PG, connect to the master and simply upload the master project, so you have original back up of the master program and implement thses codes to create and transfer pulse to intelligent slave: OB35 master side : [code]AN M100.0 //vacant memory bit = M100.0 //Pulse generated[/code] insert this newly added bit to spare messages from master to slave. it needs alittle investigation in codes. OB1 slave side: [code]AN M100.0 L S5T#10S SD T0 NOP 0 A T0 = M0.0 //CONNECTION ERROR[/code] best regards
	Demo Channel on Youtube
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11/2/2010 4:07 PM	Rate (0)
xev2008 Member Joined: 2/12/2009 Last visit: 9/3/2025 Posts: 5 Rating: (0)	Hello, Thank you for your prompt help... My problem is that the master profibus is not siemens and it is maintained by another company :-( I will try to see the LEDs status, but i am not sure if it will work... Thanx

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11/2/2010 5:05 PM	Rate (0)
hdhosseini Diamond Member Joined: 1/28/2009 Last visit: 1/5/2026 Posts: 6892 Rating: (1368)	Hi I think this will work.I was checked the status of LEDs of CPU31X-2DP in slave mode: SF(NOT RELEVANT) & (BUSF flashing) means:watchdog monitoring timed out or bus unplugged or wrong profibus address this is the case.I will check SFC51 for options on DP slaves. What is the brand of your master and also which cpu is used as slave? Best regards
	Last edited by: hdhosseini at: 11/5/2010 6:39 AM Demo Channel on Youtube
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