| ??? 12/14/05 12:10 Read: times |
#105210 - Problem Solved. Responding to: ???'s previous message |
Dear Forum Members,
Thanks yo all of you for your kind replies, The problem i was having with encoder seems to have solved. I conducted extensive tests and found that the problem of misleading decoder counts is seen only when the deocoder is working in 1X mode in 2X and 4X modes there are absolutely no errors at all. The test procedure is as follow. I connected a proximity switch that is fired when shaft completes a rotation. At start decoder count is reset. Micro starts rotating motor at 5RPM completes a rotation Rotation completion is detected by said proximity switch. After rotation completion the decoder count is read displayed on hyperterminal screen along with shaft frequency. And then frequency is increased by 1 and one rotation is completed and decoder count is displayed this process continues till 150RPM speed and then test completes. The data was captured and analysed. Theoretiaclly at 4X for every rotation the decoder counter should increament by 2000 at 2X it should increament by 1000 and at 1X by 500. Follwing are the test results of tests i conducted. RPM 4X 2X 1X ------------------------------------ 5 1991 999 61 6 3992 2000 122 7 5992 3000 293 8 7992 3999 495 9 9992 5000 743 10 11992 5999 1024 11 13992 7000 1280 12 15992 7999 1589 13 17992 9000 1833 14 19992 10001 2440 15 21992 11000 2722 16 23992 12000 3056 17 25991 13000 3381 18 27991 14000 3790 19 29991 14999 4132 20 31990 15999 4484 21 33992 17000 4881 22 35993 18001 5493 23 37993 19001 6100 24 39991 20000 6523 25 41991 21000 6996 26 43991 21999 7438 27 45990 22999 7818 28 47991 24000 8229 29 49991 25000 8718 30 51991 26000 9226 31 53991 27000 9727 32 55991 28000 10173 33 57991 29000 10610 34 59990 30000 10999 35 61991 31000 11396 36 63990 31999 11819 37 65991 32999 12249 38 67991 33998 12725 39 69991 35002 13207 40 71990 36005 13733 41 73991 37005 14242 42 75991 38006 14719 43 77991 39005 15173 44 79990 40005 15630 45 81991 41006 16082 46 83991 42005 16579 47 85991 43004 17100 48 87990 44004 17657 49 89990 45003 18141 50 91991 46003 18598 51 93993 47003 19077 52 95993 48002 19634 53 97992 49001 20126 54 99992 50000 20596 55 101992 51000 21077 56 103991 52000 21568 57 105991 53000 22129 58 107991 54000 22628 59 109991 54999 23122 60 111991 55999 23608 61 113990 56999 24098 62 115990 57999 24586 63 117990 58999 25072 64 119990 59999 25565 65 121990 60999 26058 66 123990 61999 26550 67 125989 62999 27046 68 127989 63999 27538 69 129990 64999 28034 70 131990 65999 28528 71 133988 66999 29023 72 135989 67999 29518 73 137989 68999 30013 74 139990 69999 30507 75 141989 70999 31002 It can be seen that 2X and 4X modes work very accurate at all motor speeds where as 1X mode works very bad at lower frequencies at higher freqneucies i.e beyond 60RPM performance at 1X is some what improved but not too good. Earlier i was using only 1X mode and thus was observing errors. The motor makes a lot of noise at speeds lower than 60RPM and vibrates too whereas above 60RPM it runs silent without much vibrations. At 20RPM and at 40RPM it resonantes so bad that atleast 4 times it broke its supply wires vibrating on table. The problem has been found but why this problem occurs with 1X decode and not at 2X and 4X is still a big mystry. I hope some encoder experienced forum member can tell why this strange behaviour occur with decoder. Steve/Craig the problem is solved but please dont close the thread since its only partially solved until some satisfactory info on strange 1X behaviour is posted by some kind member. Thanks & Regards, Prahlad Purohit |
