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840D Feedrate very strange behaviour

Created by: hewking102 at: 9/10/2013 9:12 PM (7 Replies)

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9/10/2013 9:12 PM	Rate (0)
hewking102 Posts: 77 Rating: (2)	Hi I am helping to find signals for monitoring of 840D Machine and one of them is "Feedrate". I was monitoring DB21.DBB4 which is described as "Feedrate Override/Z1-V1" in sinumerik 840D parameter manual trying to establish relation between feed rate set at the Operator Panel (or CNC program) and the value in DB and results are following: Operator Panel Feedrate set at: Values in DB translated to decimal: 0% 1 20% 9 40% 24 50% 25 60% 27 80% 31 100% 25 The strange thing is that when Feedrate values are set above 80 % the values in DB are dropping instead of rising. That's why i cannot use the values inside DB to detect if Feedrate is above 80% Could anybody knowledgeble about 840D explain this puzzle or advise different way of retrieving Feedrate please? Many thanks
hewking102 Posts: 77 Rating: (2)
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9/10/2013 11:02 PM	Rate (1)
Pee El Sea Gold Member Joined: 1/19/2008 Last visit: 10/2/2024 Posts: 992 Rating: (64)	Hi, Feedrate override is usually a gray code binary pattern. I don't see your problem in checking for every value over 80%. Just load each possible value and compare. Pee

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9/11/2013 12:03 AM	Rate (0)
hewking102 Posts: 77 Rating: (2)	Hi Thank you for your reply. The problem i have is that values are not unique and for examble value of 25 in DB21.DBB4 corresponds to 100% or 50% of the feedrate. I am starting to doubt that i am checking correct address. Any chance you spare me a minute and double check feedrate address from the manual below ? https://www.automation.siemens.com/doconweb/content.asp?item=6127&cd=sinumerik_simodrive_04_2010_e&scope=all Best Regards
hewking102 Posts: 77 Rating: (2)
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9/11/2013 4:54 PM	Rate (1)
Pee El Sea Gold Member Joined: 1/19/2008 Last visit: 10/2/2024 Posts: 992 Rating: (64)	Hi, I think maybe you need to start with the inputs from the feedrate override switch. These should then be transferred to DB21.DBB4 assuming you only have a single channel. They are also generally transferred into each individual axis. DB31.DBB0, DB32.DBB0 etc. But can be altered by the plc program. Have a look at section V1 in the Function Manual Basic Functions. https://www.automation.siemens.com/doconweb/pdf/SINUMERIK_SIMODRIVE_04_2010_E/FB1.pdf?p=1717#page=1717&view=FitBH,0&pagemode=none Pee

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9/11/2013 5:18 PM	Rate (0)
hewking102 Posts: 77 Rating: (2)	Hi Thank you for your reply. The address that you mentioned DB31.DBB0 shows override value and operating panel shows 100 % override so there is relation between them. The only problem is that these values are not unique (as described at the beginning of the thread) that's i don't think decoding is possible Operator Panel Feedrate set at : Values in DB translated to decimal: 0 % 1 20% 9 40% 24 50% 25 60% 27 80% 31 100% 21 Best Regards
hewking102 Posts: 77 Rating: (2)
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9/11/2013 7:50 PM	Rate (0)
SteveA Posts: 297 Rating: (41)	The gray code mapping is described here: https://www.automation.siemens.com/doconweb/showpdf.asp?item=7412&cd=sinumerik_simodrive_04_2010_e&scope=all&ResultSet=7413&CurrentItem=7413&ResultType=content Do you have the standard 23 position feedrate switch, or something different? If a different switch is used, then the machine parameters in MD12030 will be different than default. In any case, as you've seen, it's not easy to decode the current override setting from the switch position. If you can use the NC, you can look at system parameter $AC_PLC_OVR, or maybe $AC_TOTAL_OVR to determine the actual values. You can use synchronous actions to set signals based on the actual override. HTH, SteveA
SteveA Posts: 297 Rating: (41)
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9/11/2013 9:41 PM	Rate (0)
pierre_g Posts: 67 Rating: (5)	I use code like this to convert gray to binary NETWORK TITLE =mask bit 5..7 L EB 3; L B#16#1F; UW ; T #feed_gray; NETWORK TITLE =convert gray to binary L #feed_gray; PUSH ; SRW 1; XOW ; SRW 1; XOW ; SRW 1; XOW ; SRW 1; XOW ; T #Pos_bin; switch position Pierre
pierre_g Posts: 67 Rating: (5)
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This contribution was helpful to 1 thankful Users rmb_cardoso

7/21/2017 2:18 PM	Rate (0)
AutoGen_3010253 Member Joined: 1/18/2016 Last visit: 8/7/2023 Posts: 4 Rating: (0)	Hi, It is an old topic, but maybe someone is still looking for answers. Below you will find table with Gray code values, switch position and Feed value. Attachment Feedrate.JPG (392 Downloads)

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This contribution was helpful to 1 thankful Users CS Moderator

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