{"id":1750,"date":"2022-01-24T20:17:58","date_gmt":"2022-01-24T19:17:58","guid":{"rendered":"http:\/\/www.daniel.slask.pl\/?p=1750"},"modified":"2022-01-24T20:17:58","modified_gmt":"2022-01-24T19:17:58","slug":"suma-kontrolna-crc16-w-modbus-rtu","status":"publish","type":"post","link":"https:\/\/daniel.slask.pl\/m\/suma-kontrolna-crc16-w-modbus-rtu\/","title":{"rendered":"Suma kontrolna CRC16 w Modbus RTU"},"content":{"rendered":"\n<p>Wykorzystuj\u0105c protok\u00f3\u0142 Modbus RTU w transmisji szeregowej (RS485) na ko\u0144cu ramki danych wymagane jest podanie sumy kontrolnej przesy\u0142anych danych &#8211; CRC16. Jest to warto\u015b\u0107 16 bitowa obliczana wed\u0142ug odpowiedniego wzorca. Warto\u015b\u0107 t\u0105 nale\u017cy por\u00f3wna\u0107 przy odbiorze czy zgadza si\u0119 z warto\u015b\u0107 przes\u0142an\u0105 &#8211; je\u017celi tak to mo\u017cna kontynuowa\u0107 analiz\u0119 danych. W przeciwnym razie, dane nale\u017cy uzna\u0107 za b\u0142\u0119dne i nie podejmowa\u0107 pr\u00f3by ich odczytu\/analizy.<\/p>\n\n\n\n<p>Algorytm obliczenia jak i przyk\u0142adowy kod mo\u017cna znale\u017a\u0107 w dokumentacji Modbus (<a href=\"https:\/\/modbus.org\/docs\/PI_MBUS_300.pdf\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>MODBUS Over Serial Line FOR LEGACY APPLICATIONS ONLY<\/strong><\/a>) znajduj\u0105cej si\u0119 na <a rel=\"noreferrer noopener\" href=\"https:\/\/modbus.org\/specs.php\" data-type=\"URL\" data-id=\"https:\/\/modbus.org\/specs.php\" target=\"_blank\">modbus.org<\/a>. <\/p>\n\n\n\n<figure class=\"wp-block-gallery aligncenter columns-1 wp-block-gallery-1 is-layout-flex wp-block-gallery-is-layout-flex\"><ul class=\"blocks-gallery-grid\"><li class=\"blocks-gallery-item\"><figure><a href=\"http:\/\/www.daniel.slask.pl\/m\/wp-content\/uploads\/2022\/01\/Modbus_CRC_algorytm.jpg\"><img loading=\"lazy\" decoding=\"async\" width=\"150\" height=\"150\" src=\"http:\/\/www.daniel.slask.pl\/m\/wp-content\/uploads\/2022\/01\/Modbus_CRC_algorytm-150x150.jpg\" alt=\"\" data-id=\"1751\" data-full-url=\"http:\/\/www.daniel.slask.pl\/m\/wp-content\/uploads\/2022\/01\/Modbus_CRC_algorytm.jpg\" data-link=\"http:\/\/www.daniel.slask.pl\/?attachment_id=1751\" class=\"wp-image-1751\"\/><\/a><\/figure><\/li><\/ul><\/figure>\n\n\n\n<p>Obliczenie sumy kontrolnej CRC16 w j\u0119zyku C dla mikrokontroler\u00f3w AVR przedstawiam poni\u017cej. Jest on zaczerpni\u0119ty ze strony <a rel=\"noreferrer noopener\" href=\"https:\/\/www.modbustools.com\/modbus_crc16.htm\" target=\"_blank\">modbustool<\/a>, z lekkimi modyfikacjami. Bez problemu da si\u0119 j\u0105 przekonwertowa\u0107 na inny rodzaj mikrokontrolera czy to j\u0119zyka. Do funkcji tej nale\u017cy przekaza\u0107 adres tabeli w kt\u00f3rej znajduj\u0105 si\u0119 dane, kt\u00f3re b\u0119dziemy podawa\u0107 obliczaniu CRC16, oraz ilo\u015b\u0107 tych danych. W liczbie danych nie nale\u017cy uwzgl\u0119dnia\u0107 2 ostatnich odczytanych bajt\u00f3w, gdy\u017c tam znajduje si\u0119 odebrana suma kontrolna, kt\u00f3r\u0105 to b\u0119dziemy p\u00f3\u017aniej por\u00f3wnywa\u0107 z obliczon\u0105 warto\u015bci\u0105 danych odebranych w naszym uk\u0142adzie.<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"c\" class=\"language-c line-numbers\">uint16_t CRC(char *val ,uint8_t len)\n{\n\tuint8_t nTemp;\n\tuint16_t wCRCWord = 0xFFFF;\n\n\n\t   while (len--)\n\t   {\n\t      nTemp = wCRCWord  ^ *val++ ;\n\t      wCRCWord &gt;&gt;= 8;\n\t      wCRCWord ^= CRCTable[nTemp];\n\t   }\n\t   return ( wCRCWord &lt;&lt; 8 ) | (wCRCWord&gt;&gt;8);\n\n}<\/code><\/pre>\n\n\n\n<p>Zwracan\u0105 warto\u015b\u0107 nale\u017cy obr\u00f3ci\u0107, tzn 8 bit\u00f3w najstarszych nale\u017cy przestawi\u0107 z 8 bitami najm\u0142odszymi. Tabela z kt\u00f3rej odczytujemy dane jest poni\u017cej.<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"c\" class=\"language-c line-numbers\">static const uint16_t CRCTable[] = {\n0X0000, 0XC0C1, 0XC181, 0X0140, 0XC301, 0X03C0, 0X0280, 0XC241,\n0XC601, 0X06C0, 0X0780, 0XC741, 0X0500, 0XC5C1, 0XC481, 0X0440,\n0XCC01, 0X0CC0, 0X0D80, 0XCD41, 0X0F00, 0XCFC1, 0XCE81, 0X0E40,\n0X0A00, 0XCAC1, 0XCB81, 0X0B40, 0XC901, 0X09C0, 0X0880, 0XC841,\n0XD801, 0X18C0, 0X1980, 0XD941, 0X1B00, 0XDBC1, 0XDA81, 0X1A40,\n0X1E00, 0XDEC1, 0XDF81, 0X1F40, 0XDD01, 0X1DC0, 0X1C80, 0XDC41,\n0X1400, 0XD4C1, 0XD581, 0X1540, 0XD701, 0X17C0, 0X1680, 0XD641,\n0XD201, 0X12C0, 0X1380, 0XD341, 0X1100, 0XD1C1, 0XD081, 0X1040,\n0XF001, 0X30C0, 0X3180, 0XF141, 0X3300, 0XF3C1, 0XF281, 0X3240,\n0X3600, 0XF6C1, 0XF781, 0X3740, 0XF501, 0X35C0, 0X3480, 0XF441,\n0X3C00, 0XFCC1, 0XFD81, 0X3D40, 0XFF01, 0X3FC0, 0X3E80, 0XFE41,\n0XFA01, 0X3AC0, 0X3B80, 0XFB41, 0X3900, 0XF9C1, 0XF881, 0X3840,\n0X2800, 0XE8C1, 0XE981, 0X2940, 0XEB01, 0X2BC0, 0X2A80, 0XEA41,\n0XEE01, 0X2EC0, 0X2F80, 0XEF41, 0X2D00, 0XEDC1, 0XEC81, 0X2C40,\n0XE401, 0X24C0, 0X2580, 0XE541, 0X2700, 0XE7C1, 0XE681, 0X2640,\n0X2200, 0XE2C1, 0XE381, 0X2340, 0XE101, 0X21C0, 0X2080, 0XE041,\n0XA001, 0X60C0, 0X6180, 0XA141, 0X6300, 0XA3C1, 0XA281, 0X6240,\n0X6600, 0XA6C1, 0XA781, 0X6740, 0XA501, 0X65C0, 0X6480, 0XA441,\n0X6C00, 0XACC1, 0XAD81, 0X6D40, 0XAF01, 0X6FC0, 0X6E80, 0XAE41,\n0XAA01, 0X6AC0, 0X6B80, 0XAB41, 0X6900, 0XA9C1, 0XA881, 0X6840,\n0X7800, 0XB8C1, 0XB981, 0X7940, 0XBB01, 0X7BC0, 0X7A80, 0XBA41,\n0XBE01, 0X7EC0, 0X7F80, 0XBF41, 0X7D00, 0XBDC1, 0XBC81, 0X7C40,\n0XB401, 0X74C0, 0X7580, 0XB541, 0X7700, 0XB7C1, 0XB681, 0X7640,\n0X7200, 0XB2C1, 0XB381, 0X7340, 0XB101, 0X71C0, 0X7080, 0XB041,\n0X5000, 0X90C1, 0X9181, 0X5140, 0X9301, 0X53C0, 0X5280, 0X9241,\n0X9601, 0X56C0, 0X5780, 0X9741, 0X5500, 0X95C1, 0X9481, 0X5440,\n0X9C01, 0X5CC0, 0X5D80, 0X9D41, 0X5F00, 0X9FC1, 0X9E81, 0X5E40,\n0X5A00, 0X9AC1, 0X9B81, 0X5B40, 0X9901, 0X59C0, 0X5880, 0X9841,\n0X8801, 0X48C0, 0X4980, 0X8941, 0X4B00, 0X8BC1, 0X8A81, 0X4A40,\n0X4E00, 0X8EC1, 0X8F81, 0X4F40, 0X8D01, 0X4DC0, 0X4C80, 0X8C41,\n0X4400, 0X84C1, 0X8581, 0X4540, 0X8701, 0X47C0, 0X4680, 0X8641,\n0X8201, 0X42C0, 0X4380, 0X8341, 0X4100, 0X81C1, 0X8081, 0X4040 };\n\n\n<\/code><\/pre>\n\n\n\n<p>Poni\u017cej przedstawiam spos\u00f3b z wykorzystaniem dw\u00f3ch tabel, w kt\u00f3rych kom\u00f3rki s\u0105 8 bitowe. Po po\u0142\u0105czeniu ka\u017cdej pozycji z tabel wychodzi nam warto\u015b\u0107 jak w tabeli z kom\u00f3rkami 16 bitowymi. Spos\u00f3b obliczania jest taki sam, z t\u0105 r\u00f3\u017cnic\u0105, \u017ce operujemy na zmiennych 8 bitowych.<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"c\" class=\"language-c\">static const uint8_t RTU_CRC_Hi[]  = {\n\t\t0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81,\n\t\t0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0,\n\t\t0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01,\n\t\t0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41,\n\t\t0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81,\n\t\t0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,\n\t\t0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01,\n\t\t0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,\n\t\t0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81,\n\t\t0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0,\n\t\t0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01,\n\t\t0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,\n\t\t0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81,\n\t\t0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0,\n\t\t0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01,\n\t\t0x40\n} ;\n\nstatic const uint8_t RTU_CRC_Lo[]  = {\n\t\t0x00, 0xC0, 0xC1, 0x01, 0xC3, 0x03, 0x02, 0xC2, 0xC6, 0x06, 0x07, 0xC7, 0x05, 0xC5, 0xC4,\n\t\t0x04, 0xCC, 0x0C, 0x0D, 0xCD, 0x0F, 0xCF, 0xCE, 0x0E, 0x0A, 0xCA, 0xCB, 0x0B, 0xC9, 0x09,\n\t\t0x08, 0xC8, 0xD8, 0x18, 0x19, 0xD9, 0x1B, 0xDB, 0xDA, 0x1A, 0x1E, 0xDE, 0xDF, 0x1F, 0xDD,\n\t\t0x1D, 0x1C, 0xDC, 0x14, 0xD4, 0xD5, 0x15, 0xD7, 0x17, 0x16, 0xD6, 0xD2, 0x12, 0x13, 0xD3,\n\t\t0x11, 0xD1, 0xD0, 0x10, 0xF0, 0x30, 0x31, 0xF1, 0x33, 0xF3, 0xF2, 0x32, 0x36, 0xF6, 0xF7,\n\t\t0x37, 0xF5, 0x35, 0x34, 0xF4, 0x3C, 0xFC, 0xFD, 0x3D, 0xFF, 0x3F, 0x3E, 0xFE, 0xFA, 0x3A,\n\t\t0x3B, 0xFB, 0x39, 0xF9, 0xF8, 0x38, 0x28, 0xE8, 0xE9, 0x29, 0xEB, 0x2B, 0x2A, 0xEA, 0xEE,\n\t\t0x2E, 0x2F, 0xEF, 0x2D, 0xED, 0xEC, 0x2C, 0xE4, 0x24, 0x25, 0xE5, 0x27, 0xE7, 0xE6, 0x26,\n\t\t0x22, 0xE2, 0xE3, 0x23, 0xE1, 0x21, 0x20, 0xE0, 0xA0, 0x60, 0x61, 0xA1, 0x63, 0xA3, 0xA2,\n\t\t0x62, 0x66, 0xA6, 0xA7, 0x67, 0xA5, 0x65, 0x64, 0xA4, 0x6C, 0xAC, 0xAD, 0x6D, 0xAF, 0x6F,\n\t\t0x6E, 0xAE, 0xAA, 0x6A, 0x6B, 0xAB, 0x69, 0xA9, 0xA8, 0x68, 0x78, 0xB8, 0xB9, 0x79, 0xBB,\n\t\t0x7B, 0x7A, 0xBA, 0xBE, 0x7E, 0x7F, 0xBF, 0x7D, 0xBD, 0xBC, 0x7C, 0xB4, 0x74, 0x75, 0xB5,\n\t\t0x77, 0xB7, 0xB6, 0x76, 0x72, 0xB2, 0xB3, 0x73, 0xB1, 0x71, 0x70, 0xB0, 0x50, 0x90, 0x91,\n\t\t0x51, 0x93, 0x53, 0x52, 0x92, 0x96, 0x56, 0x57, 0x97, 0x55, 0x95, 0x94, 0x54, 0x9C, 0x5C,\n\t\t0x5D, 0x9D, 0x5F, 0x9F, 0x9E, 0x5E, 0x5A, 0x9A, 0x9B, 0x5B, 0x99, 0x59, 0x58, 0x98, 0x88,\n\t\t0x48, 0x49, 0x89, 0x4B, 0x8B, 0x8A, 0x4A, 0x4E, 0x8E, 0x8F, 0x4F, 0x8D, 0x4D, 0x4C, 0x8C,\n\t\t0x44, 0x84, 0x85, 0x45, 0x87, 0x47, 0x46, 0x86, 0x82, 0x42, 0x43, 0x83, 0x41, 0x81, 0x80,\n\t\t0x40\n};<\/code><\/pre>\n\n\n\n<p>W kodzie jak poni\u017cej, warto\u015b\u0107 CRC jest sum\u0105 logiczn\u0105 obliczonych dw\u00f3ch warto\u015bci z przesuni\u0119ciem o 8 bit\u00f3w w lewo warto\u015bci HI.<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"c\" class=\"language-c\">uint16_t CRC(char *val ,uint8_t len)\n{\n\n\n\tuint8_t crc_hi=0xff, crc_lo=0xff;\n\tuint8_t _temp;\n\n\n\twhile(len--){\n\t\t_temp = *val++ ^ crc_lo ;\n\t\tcrc_hi = crc_hi ^ RTU_CRC_Hi[_temp];\n\t\tcrc_lo = RTU_CRC_Lo[_temp];\n\t}\n\n\treturn (crc_hi &lt;&lt; 8 | crc_lo);\n}<\/code><\/pre>\n\n\n\n<p>Z ciekawych link\u00f3w polecam ten <a href=\"https:\/\/www.lammertbies.nl\/comm\/info\/crc-calculation\" target=\"_blank\" rel=\"noreferrer noopener\">tutaj<\/a>, dzi\u0119ki kt\u00f3remu mo\u017cemy obliczy\u0107 sum\u0119 kontroln\u0105 CRC16.<\/p>\n\n\n\n<p>I to by\u0142oby na tyle. Je\u017celi program\/kod nie b\u0119dzie dzia\u0142a\u0142, dajcie zna\u0107 w komentarzach.<br>Pozdrawiam.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Wykorzystuj\u0105c protok\u00f3\u0142 Modbus RTU w transmisji szeregowej (RS485) na ko\u0144cu ramki danych wymagane jest podanie sumy kontrolnej przesy\u0142anych danych &#8211; CRC16. Jest to warto\u015b\u0107 16 bitowa obliczana wed\u0142ug odpowiedniego wzorca. Warto\u015b\u0107 t\u0105 nale\u017cy por\u00f3wna\u0107 przy odbiorze czy zgadza si\u0119 z&#8230;<br \/><a class=\"read-more-button\" href=\"https:\/\/daniel.slask.pl\/m\/suma-kontrolna-crc16-w-modbus-rtu\/\">Wi\u0119cej<\/a><\/p>\n","protected":false},"author":1,"featured_media":1755,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_exactmetrics_skip_tracking":false,"_exactmetrics_sitenote_active":false,"_exactmetrics_sitenote_note":"","_exactmetrics_sitenote_category":0,"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[7],"tags":[12,33,233,234,231,191,232,235],"views":241,"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"https:\/\/daniel.slask.pl\/m\/wp-content\/uploads\/2022\/01\/CRC16.jpg","jetpack_shortlink":"https:\/\/wp.me\/pcPgV3-se","_links":{"self":[{"href":"https:\/\/daniel.slask.pl\/m\/wp-json\/wp\/v2\/posts\/1750"}],"collection":[{"href":"https:\/\/daniel.slask.pl\/m\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/daniel.slask.pl\/m\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/daniel.slask.pl\/m\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/daniel.slask.pl\/m\/wp-json\/wp\/v2\/comments?post=1750"}],"version-history":[{"count":3,"href":"https:\/\/daniel.slask.pl\/m\/wp-json\/wp\/v2\/posts\/1750\/revisions"}],"predecessor-version":[{"id":1754,"href":"https:\/\/daniel.slask.pl\/m\/wp-json\/wp\/v2\/posts\/1750\/revisions\/1754"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/daniel.slask.pl\/m\/wp-json\/wp\/v2\/media\/1755"}],"wp:attachment":[{"href":"https:\/\/daniel.slask.pl\/m\/wp-json\/wp\/v2\/media?parent=1750"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/daniel.slask.pl\/m\/wp-json\/wp\/v2\/categories?post=1750"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/daniel.slask.pl\/m\/wp-json\/wp\/v2\/tags?post=1750"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}