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FM353 SYNC BIT

Created by: vipz at: 1/4/2014 8:38 AM (1 Replies)

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1/4/2014 8:38 AM	Rate (0)
vipz Gold Member Joined: 9/2/2012 Last visit: 11/27/2024 Posts: 711 Rating: (30)	Hai all, Recently i have attented one service call at one of our customer place. There they have used s7-300 plc and FM 353 stepper module. Third party stepper drive is connected to fm353 module. To start the motor, one digital output is configured in PLC, which is not getting high. When i traced the program, found that "synchronisation bit" (db1.dbx25.0 -- used standard DB given in sample program) is used as interlock for this particular Digital Output is not high. This is getting writed internaly by fm353, but i dont know why it is not coming and how to check why it is not coming. For running the machine, i have temporarly bypassed this bit, at that time machine is working fine. Original backup of program was not available, so couldnt able to "dig" much. can anybody suggest how i can solve this issue ??
	With Best Regards VIPZ
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1/29/2014 10:12 AM	Rate (0)
hts13 Advanced Member Joined: 10/1/2007 Last visit: 11/26/2024 Posts: 10 Rating: (2)	Hi Vipz, the FM 353 (1axis stepper controller with pulse/direction interface and without encoder feedback) does need to by synchronised when operating modes Incremental, MDI, Automatic are used, before you start the movement. For operating modes Jog, open loop control and refernce point aproach the SYNC(DBX25.0) bit must not be true. The synchronisation is needed that the measurement system of the FM and the measurement of the are in syncand a position to the desired position is possible. The Sync Bit (DBX25.0)will become TRUE, after the operating mode "refernce point approach" is finished sucessful (FM is searching for a refernce signal - might be a BERO, depends on the configuration of the FM). You may also use the function "set refernce point", to set the (actual menchanical)position to a desired value and the SYNC Bit (DBX25.0)will become true as well. The SYNC bit (DBX25.0)will be FALSE after each startup, after each startup a refernce poinnt approach/setting is needed always. The SYNC Bit (DBX25.0) will become false when the Bit "DRV_EN" (DBX15.7)is set to false (enable of movement) or when the Bit "SERVO_EN" (DBX34.0) becomes false. Additionally also Alarmsthe FM is detectingmay result in loosing the sync Bit. Since this is a running application and seemd to work before, I suggest to find out the latest changes (Program, Lectronic, mechanic,...) in the application and check if this may be causing the missing SYNC Bit. It might be possible that the reference point apporach was not finished since the Refernce Point Input is missing or similar. The manual of the FM 353 can be found at http://support.automation.siemens.com/WW/view/de/60677209Most of the informations needed are un chapter 6 (description of the programming) and 9 (description of the functions) and chapter 5 (parameter description) I would suggest to contact the Technical Support (create a Service Request) and you will be helped more individual! Bernhard
	Last edited by: hts13 at: 1/29/2014 10:12 AM
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