FB Read actual position

[shoaibmoin 0]

Hi i got this FB from Omron lib called NCF205A read actual position. the AC servo motor i am using is R88M-G10030H-s2 and drive is r88D-GN-02H-ML2 with NCF471 card the problem is FB gives me the position but in negative readings i don't understand why it does it. the servo is going in clockwise direction. thanks for any help _NCF205A_ReadActualPosition_DINT.pdf

[ParaffinPower 13]

Hello When you say cw, is that looking at the shaft or from behind the shaft. Looking at the shaft, cw is reverse hence negative values. Pn00 (I think) in the drive swaps to cw being forward. The axis current position appears in the 'axis operating input' memory area automatically; you don't need to use an Fb. I use ncf often, and never use the fb's. I've made an xls to generate all the axis and ncf symbols If you want it? Pp

[shoaibmoin 0]

Thanks for reply Im looking the shaft from front side and yes i also tried watching the value directly using ncf symbols and even that value is displayed in negative. would it effect the program if i scale that value with -1.0000E in hmi to display it in m/min?

[ParaffinPower 13]

If it's going backwards then the position will be decreasing regardless of where you monitor it. You must be telling it to go backwards, though. You would be able to put the units into m/min in the drive (or a multiple thereof) and read directly - this will still be negative though. Either multiply by -1 or do it on the hmi. You could reverse the servo (see my first post) and save yourself a job. Pp

[ParaffinPower 13]

If it's going backwards then the position will be decreasing regardless of where you monitor it. You must be telling it to go backwards, though. You would be able to put the units into m/min in the drive (or a multiple thereof) and read directly - this will still be negative though. Either multiply by -1 or do it on the hmi. You could reverse the servo (see my first post) and save yourself a job. Pp