{"id":13350,"date":"2019-03-05T06:30:47","date_gmt":"2019-03-05T05:30:47","guid":{"rendered":"https:\/\/mag.ebmpapst.com\/en\/?p=13350"},"modified":"2024-03-12T17:54:39","modified_gmt":"2024-03-12T16:54:39","slug":"the-formula-for-the-data-transfer-time","status":"publish","type":"post","link":"https:\/\/mag.ebmpapst.com\/en\/allgemein\/the-formula-for-the-data-transfer-time_13350\/","title":{"rendered":"The formula for the data transfer time"},"content":{"rendered":"

Markus Wein\u00adgart, Head of Depart\u00adment Elec\u00adtronics, ebm-papst Land\u00adshut<\/p><\/div><\/div>\n

In the auto\u00admo\u00adtive sector, the LIN bus is a long-estab\u00adlished commu\u00adni\u00adca\u00adtions solu\u00adtion for networking sensors and actu\u00ada\u00adtors and their control devices. In view of the success of smart home appli\u00adca\u00adtions, the serial fieldbus system is gaining rapidly in impor\u00adtance in the heating sector as LIN bus commu\u00adni\u00adca\u00adtion provides a lean solu\u00adtion for connecting compo\u00adnents such as pumps or gas blowers and thus making smart condensing boilers possible.<\/p>\n

The LIN bus is a single-master, multi-slave system. The \u00admaster \u200a\u2014\u200ain a condensing boiler, the elec\u00adtronic controller\u200a\u2014\u200adeter\u00admines when the slave\u200a\u2014\u200afor example, the blower\u200a\u2014\u200ashould provide data or carry out commands. This takes place at cyclical inter\u00advals according to a time\u00adtable kept in the master. This clear schedule defines which infor\u00adma\u00adtion is to flow and when. For our gas blowers, we recom\u00admend retrieving the data rele\u00advant to control systems, such as the speed, every fifty millisec\u00adonds.<\/p>\n

Infor\u00adma\u00adtion as key<\/h2>\n

For data that do not change so often, such as temper\u00ada\u00adture or power consump\u00adtion, longer inter\u00advals are suffi\u00adcient. For defining the schedule, that makes it impor\u00adtant to know the data transfer time for the various infor\u00adma\u00adtion packets. This is similar to plan\u00adning in produc\u00adtion, where it is also neces\u00adsary to take timing into consid\u00ader\u00ada\u00adtion when sequencing the indi\u00advidual steps in a process.<\/p>\n

Example of a LIN message for a gas blower<\/p><\/div><\/div>\n

How long does it take to transmit a data packet? To answer this ques\u00adtion, it helps to take a look at the typical struc\u00adture of a LIN message (see example). In the LIN bus, it may include a maximum of 64 bits. But this infor\u00adma\u00adtion is not enough to calcu\u00adlate the transfer time. A so-called \u201cover\u00adhead\u201d is also needed, because before data retrieval starts, the master sends synchro\u00adniza\u00adtion pulses to fore\u00adwarn the slave so it can adjust to the master\u2019s clock rate.<\/p>\n

All in order<\/h2>\n

In addi\u00adtion, a packet iden\u00adti\u00adfier (PID) is sent with a checksum for every transfer to announce the data packet\u2019s contents and verify whether the data are trans\u00adferred correctly. On top of that, a safety buffer of 40 percent is added since, as in produc\u00adtion, some\u00adtimes a step can take longer than usual. But the produc\u00adtion plan must not be allowed to get mixed up because of that.<\/p>\n

The maximum data transfer time is calcu\u00adlated from the formula above. The term t Frame_Nom is the time required to transfer the data packet with the content infor\u00adma\u00adtion including over\u00adhead. It is calcu\u00adlated from the number of bytes multi\u00adplied by ten. This factor is comprised of the number of bits per byte (eight) and a start and a stop bit per byte. The number of bits in the over\u00adhead is given as 44. The para\u00admeter t bit = baud rate-1 desig\u00adnates the baud rate, a unit that expresses trans\u00admis\u00adsion speed. In a LIN bus, bit rates of 19.2 kbit per second are typical. For this value, a bit transfer time of t bit = (19.2 kbit\/s)-1 = 52 \u03bcs results. So a LIN message with 64 bits has a maximum data transfer time of about nine millisec\u00adonds.\u2002<\/p>\n","protected":false},"excerpt":{"rendered":"

In the auto\u00admo\u00adtive sector, the LIN bus is a long-estab\u00adlished commu\u00adni\u00adca\u00adtions solu\u00adtion for networking sensors and actu\u00ada\u00adtors and their control devices. In view of the success of smart home appli\u00adca\u00adtions, the serial fieldbus system is gaining rapidly in impor\u00adtance in the heating sector as LIN bus commu\u00adni\u00adca\u00adtion provides a lean solu\u00adtion for connecting compo\u00adnents such [\u2026]<\/p>\n","protected":false},"author":25,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"wp_typography_post_enhancements_disabled":false,"footnotes":""},"categories":[1,5,4,15],"tags":[],"class_list":["post-13350","post","type-post","status-publish","format-standard","hentry","category-allgemein","category-electronics","category-insights","category-telecommunication"],"acf":[],"_links":{"self":[{"href":"https:\/\/mag.ebmpapst.com\/en\/wp-json\/wp\/v2\/posts\/13350","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/mag.ebmpapst.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mag.ebmpapst.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mag.ebmpapst.com\/en\/wp-json\/wp\/v2\/users\/25"}],"replies":[{"embeddable":true,"href":"https:\/\/mag.ebmpapst.com\/en\/wp-json\/wp\/v2\/comments?post=13350"}],"version-history":[{"count":2,"href":"https:\/\/mag.ebmpapst.com\/en\/wp-json\/wp\/v2\/posts\/13350\/revisions"}],"predecessor-version":[{"id":20750,"href":"https:\/\/mag.ebmpapst.com\/en\/wp-json\/wp\/v2\/posts\/13350\/revisions\/20750"}],"wp:attachment":[{"href":"https:\/\/mag.ebmpapst.com\/en\/wp-json\/wp\/v2\/media?parent=13350"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mag.ebmpapst.com\/en\/wp-json\/wp\/v2\/categories?post=13350"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mag.ebmpapst.com\/en\/wp-json\/wp\/v2\/tags?post=13350"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}