Posted 11 Feb 2018 (edited) I connected between Altivar 71 VSD drive and Modicon M340 PLC through MODBUS RTU RS485 and the communication is ok, now i want write a command word using Write_var function to control the VSD but I find very confusing. first : it's written in cataloug that bits from 0 to 15 can be assigned to commands , is that done from HMI? i can't find anywhere on HMI. second : in the function (both read and write) obj element can be int or bool bit but the EMIS element in 'write_var' function (data going to VSD registers) only accepted if it's array of int not bool so i can't trigger the bits i want !! third : like the picture the VSD showing it's in NST mode and it says that it won't start until hex value of 6 written to command word but the catalogue says that only bit 0 is assigned(to forword command) and other 15 bits are free for user to assign and 6 in hex (0110) bit 1 and bit 2 still not assigned to any thing !! i hope anyone could help Edited 12 Feb 2018 by engMoH Share this post Link to post Share on other sites
Posted 12 Feb 2018 Hi engMoh, do you use I/O scanner on ATV71? If yes, then just use WRITE_VAR block to write 2 registers at address 0. The first register will be ATV71 command word (value 16#0006 -> 16#000 7 -> 16#000 F for starting ATV) and second register will be RPM of the motor. Share this post Link to post Share on other sites
Posted 14 Feb 2018 Hi Quant, thanks it worked when i write 6 then 7 but in the address 8501 not 0 . now i want to make a ladder program to make it Automatic i tried to make ladder program to write 6 then 7 in same register but it keep writing 6 then 7 forever so the motor just make sound but is not moving. can you help me on that ? it has to write 6 then 7 for one time and not keep writing them forever, thanks in advance. Share this post Link to post Share on other sites
Posted 15 Feb 2018 the easiest way is to use EQ blocks and compare actual status word or status bits with predefined values and then trigger the MOVE blocks, which moves 6,7, to to command word. Share this post Link to post Share on other sites
Posted 16 Feb 2018 (edited) Hi Quant thank you again, it worked now i can operate the drive through ladder diagram. still one small problem to end it i hope to solve it. every time i download a code on plc the drive give modbus fault and won't operate until i disconnect power to VSD then reconnect it again. i want to reset fault when i press start. i found this in catalogue, and what i get is that i should write 177 in the address 7124 every time in the starting is that right? didn't try it yet, if you have any thoughts please share it with me. Edited 17 Feb 2018 by engMoH Share this post Link to post Share on other sites
Posted 5 Mar 2018 Dear sir Please help me. I have altvar 71 connect in plc telemqunica plc 7-3 under network fipo bus. The drive is working good but I have two problem 1-the drive some time random the speed is decrease and increase overshoot 2-the drive not stop breaking when press process stop switch but stop freewheel (the break resistance is connected ) Share this post Link to post Share on other sites
Posted 8 Mar 2018 Dear sir Please help me. I have altvar 71 connect in plc telemqunica plc 7-3 under network fipo bus. The drive is working good but I have two problem 1-the drive some time random the speed is decrease and increase overshoot 2-the drive not stop breaking when press process stop switch but stop freewheel (the break resistance is connected ) Share this post Link to post Share on other sites
Posted 9 Mar 2018 hi Ramadan i am not expert but i have the same drive and i got it work through MODBUS serial RS485 and it is very easy you can try if your plc has serial port but i never use fipo bus speed shouldn't be random it may be a defect in the gearbox of your motor you can use encoder and make a feedback loop to the driver Share this post Link to post Share on other sites
Posted 9 Mar 2018 Dear sir Thank you for interest.the drives atv66 are working good in the network but the atv66 is absolutely so we were replaced atv66 by atv71. But all drives atv71 in the network fipo bus are the same problem. The drives are working in open loop not used encoder . Share this post Link to post Share on other sites