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using BSEND and BRCV in CFC

Created by: dangerous at: 7/28/2006 8:56 AM (7 Replies)

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7/28/2006 8:56 AM	Rate (0)
dangerous Posts: 35 Rating: (1)	Hi, I am generating some software for a Modbus link in CFC and was wondering if anyone has seen examples of using BSEND / BRCV. I could also write them in SCL but I cannot find any examples of this either. Kind Regards dangerous
dangerous Posts: 35 Rating: (1)
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7/28/2006 9:46 AM	Rate (1)
Wizard Diamond Member Joined: 4/24/2006 Last visit: 12/20/2024 Posts: 8786 Rating: (1172)	Hello dangerous, Have you seen the following links: http://support.automation.siemens.com/WW/view/en/6232316 http://support.automation.siemens.com/WW/view/en/23175255 http://support.automation.siemens.com/WW/view/en/20982954 http://support.automation.siemens.com/WW/view/en/20987358 http://support.automation.siemens.com/WW/view/en/344034 Best regards, Wizard

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7/28/2006 10:13 AM	Rate (0)
dangerous Posts: 35 Rating: (1)	Wizard I had not seen those samples, I'll have a look through them now. Many Thanks dangerous
dangerous Posts: 35 Rating: (1)
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7/29/2006 2:55 AM	Rate (0)
Dec Gold Expert Joined: 5/19/2006 Last visit: 12/3/2024 Posts: 549 Rating: (107)	You can’t use BSEND & BRCV for Modbus protocol;These SFBs are design for S7 connections only. If your intention was to exchange data with other S7 PLC, in PCS7 lib there are some ready made functions FB207-FB210 Dec

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8/15/2006 11:55 AM	Rate (0)
dangerous Posts: 35 Rating: (1)	Hi Dec, thanks for your reply however I should point out that I have used BSEND and BRCV with modbus protocol many times before using STL, I just had not done it in CFC. I am open to suggestions though if you can let me know why using FB207-FB210 would be better! Please see attachement for BSEND/BRCV example. Thanks again Attachment p1_ModbusIF1.zip (964 Downloads)
dangerous Posts: 35 Rating: (1)
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8/16/2006 3:41 AM	Rate (0)
Dec Gold Expert Joined: 5/19/2006 Last visit: 12/3/2024 Posts: 549 Rating: (107)	hi dangerous, You might be communicating with modbus slaves using some sort of PC Gateway that understand S7 protocol (maybe have S7 Softnet IE)in one side and convert -> transfer the modbustelegram to a Modbus master driver on the other side. [;)] Take a look in NetPro what kind of connectionsare the ones with wIDconnection number. Should be S7 Connections. Dec

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9/15/2006 10:05 PM	Rate (0)
engyn Posts: 1 Rating: (0)	hello wizard, i have usedn coupling between 2 AS417 CPUs but when we switch-off the CPUs at maintenance time for a long then at switch-on time the coupling link sometimes frozen or no connection can established.what i shall do except downloading the netpro project to CPUs because when i download it the cpus will sto and restart and i do not want it. on send blcok the error bit is "1" now.
engyn Posts: 1 Rating: (0)
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9/19/2006 9:08 AM	Rate (0)
Wizard Diamond Member Joined: 4/24/2006 Last visit: 12/20/2024 Posts: 8786 Rating: (1172)	Hello Engyn, Are both CPU's started at the same time? Which one is started first, one of your CPU's is the active connection partner! Best regards, Wizard

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