{"id":4543,"date":"2015-09-29T16:32:34","date_gmt":"2015-09-29T09:32:34","guid":{"rendered":"http:\/\/snt.com.vn\/blog\/?p=4543"},"modified":"2015-09-29T16:32:34","modified_gmt":"2015-09-29T09:32:34","slug":"c%c6%a1-b%e1%ba%a3n-v%e1%bb%81-chu%e1%ba%a9n-giao-ti%e1%ba%bfp-rs232","status":"publish","type":"post","link":"https:\/\/snt.com.vn\/blog\/c%c6%a1-b%e1%ba%a3n-v%e1%bb%81-chu%e1%ba%a9n-giao-ti%e1%ba%bfp-rs232\/","title":{"rendered":"C\u01a1 b\u1ea3n v\u1ec1 chu\u1ea9n giao ti\u1ebfp RS232"},"content":{"rendered":"

1. T\u1ed5ng quan chu\u1ea9n RS232<\/strong>
\nC\u00f3 hai phi\u00ean b\u1ea3n RS232 \u0111\u01b0\u1ee3c l\u01b0u h\u00e0nh trong th\u1eddi gian t\u01b0\u01a1ng \u0111\u1ed1i d\u00e0i l\u00e0 RS232B v\u00e0 RS232C.
\nNh\u01b0ng cho \u0111\u1ebfn nay th\u00ec phi\u00ean b\u1ea3n RS232B c\u0169 th\u00ec \u00edt \u0111\u01b0\u1ee3c d\u00f9ng c\u00f2n RS232C hi\u1ec7n v\u1eabn \u0111\u01b0\u1ee3c d\u00f9ng v\u00e0 t\u1ed3n t\u1ea1i th\u01b0\u1eddng \u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 t\u00ean ng\u1eafn g\u1ecdn l\u00e0 chu\u1ea9n RS232
\nC\u00e1c m\u00e1y t\u00ednh th\u01b0\u1eddng c\u00f3 1 ho\u1eb7c 2 c\u1ed5ng n\u1ed1i ti\u1ebfp theo chu\u1ea9n RS232C \u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 c\u1ed5ng Com. Ch\u00fang \u0111\u01b0\u1ee3c d\u00f9ng gh\u00e9p n\u1ed1i cho chu\u1ed9t, modem, thi\u1ebft b\u1ecb \u0111o l\u01b0\u1eddng…
\nTr\u00ean main m\u00e1y t\u00ednh c\u00f3 lo\u1ea1i 9 ch\u00e2n ho\u1eb7c lo\u1ea1i 25 ch\u00e2n t\u00f9y v\u00e0o \u0111\u1eddi m\u00e1y v\u00e0 main c\u1ee7a m\u00e1y t\u00ednh. Vi\u1ec7c thi\u1ebft k\u1ebf giao ti\u1ebfp v\u1edbi c\u1ed5ng RS232 c\u0169ng t\u01b0\u01a1ng \u0111\u1ed1i d\u1ec5 d\u00e0ng, \u0111\u1eb7c bi\u1ec7t khi ch\u1ecdn ch\u1ebf \u0111\u1ed9 ho\u1ea1t \u0111\u1ed9ng l\u00e0 kh\u00f4ng \u0111\u1ed3ng b\u1ed9 v\u00e0 t\u1ed1c \u0111\u1ed9 truy\u1ec1n d\u1eef li\u1ec7u th\u1ea5p
\n\"\"<\/a>
\n<\/p>\n

2. \u01afu \u0111i\u1ec3m c\u1ee7a giao di\u1ec7n n\u1ed1i ti\u1ebfp RS232<\/strong>
\n+ Kh\u1ea3 n\u0103ng ch\u1ed1ng nhi\u1ec5u c\u1ee7a c\u00e1c c\u1ed5ng n\u1ed1i ti\u1ebfp cao
\n+ Thi\u1ebft b\u1ecb ngo\u1ea1i vi c\u00f3 th\u1ec3 th\u00e1o l\u1eafp ngay c\u1ea3 khi m\u00e1y t\u00ednh \u0111ang \u0111\u01b0\u1ee3c c\u1ea5p \u0111i\u1ec7n
\n+ C\u00e1c m\u1ea1ch \u0111i\u1ec7n \u0111\u01a1n gi\u1ea3n c\u00f3 th\u1ec3 nh\u1eadn \u0111\u01b0\u1ee3c \u0111i\u1ec7n \u00e1p ngu\u1ed3n nu\u00f4i qua c\u00f4ng n\u1ed1i ti\u1ebfp<\/p>\n

3. Nh\u1eefng \u0111\u1eb7c \u0111i\u1ec3m c\u1ea7n l\u01b0u \u00fd trong chu\u1ea9n RS232<\/strong>
\n+ Trong chu\u1ea9n RS232 c\u00f3 m\u1ee9c gi\u1edbi h\u1ea1n tr\u00ean v\u00e0 d\u01b0\u1edbi (logic 0 v\u00e0 1) l\u00e0 +-12V. Hi\u1ec7n nay \u0111ang \u0111\u01b0\u1ee3c c\u1ed1 \u0111\u1ecbnh tr\u1edf kh\u00e1ng t\u1ea3i trong ph\u1ea1m vi t\u1eeb 3000 ohm – 7000 ohm
\n+ M\u1ee9c logic 1 c\u00f3 \u0111i\u1ec7n \u00e1p n\u1eb1m trong kho\u1ea3ng -3V \u0111\u1ebfn -12V, m\u1ee9c logic 0 t\u1eeb +-3V \u0111\u1ebfn 12V
\n+ T\u1ed1c \u0111\u1ed9 truy\u1ec1n nh\u1eadn d\u1eef li\u1ec7u c\u1ef1c \u0111\u1ea1i l\u00e0 100kbps ( ng\u00e0y nay c\u00f3 th\u1ec3 l\u1edbn h\u01a1n)
\n+ C\u00e1c l\u1ed1i v\u00e0o ph\u1ea3i c\u00f3 \u0111i\u1ec7n dung nh\u1ecf h\u01a1n 2500pF
\n+ Tr\u1edf kh\u00e1ng t\u1ea3i ph\u1ea3i l\u1edbn h\u01a1n 3000 ohm nh\u01b0ng ph\u1ea3i nh\u1ecf h\u01a1n 7000 ohm
\n+ \u0110\u1ed9 d\u00e0i c\u1ee7a c\u00e1p n\u1ed1i gi\u1eefa m\u00e1y t\u00ednh v\u00e0 thi\u1ebft b\u1ecb ngo\u1ea1i vi gh\u00e9p n\u1ed1i qua c\u1ed5ng n\u1ed1i ti\u1ebfp RS232 kh\u00f4ng v\u01b0\u1ee3t qua 15m n\u1ebfu ch\u00fang ta kh\u00f4ng s\u1eed model
\n+ C\u00e1c gi\u00e1 tr\u1ecb t\u1ed1c \u0111\u1ed9 truy\u1ec1n d\u1eef li\u1ec7u chu\u1ea9n : 50,75,110,750,300,600,1200,2400,4800,9600,19200,28800,38400….56600,115200 bps
\n\"\"<\/a><\/p>\n

4. C\u00e1c m\u1ee9c \u0111i\u1ec7n \u00e1p \u0111\u01b0\u1eddng truy\u1ec1n<\/strong>
\nRS 232 s\u1eed d\u1ee5ng ph\u01b0\u01a1ng th\u1ee9c truy\u1ec1n th\u00f4ng kh\u00f4ng \u0111\u1ed1i x\u1ee9ng, t\u1ee9c l\u00e0 s\u1eed d\u1ee5ng t\u00edn hi\u1ec7u \u0111i\u1ec7n \u00e1p ch\u00eanh l\u1ec7ch gi\u1eefa m\u1ed9t d\u00e2y d\u1eabn v\u00e0 \u0111\u1ea5t. Do \u0111\u00f3 ngay t\u1eeb \u0111\u1ea7u ti\u00ean ra \u0111\u1eddi n\u00f3 \u0111\u00e3 mang v\u1ebb l\u1ed7i th\u1eddi c\u1ee7a chu\u1ea9n TTL, n\u00f3 v\u1ea5n s\u1eed d\u1ee5ng c\u00e1c m\u1ee9c \u0111i\u1ec7n \u00e1p t\u01b0\u01a1ng th\u00edch TTL \u0111\u1ec3 m\u00f4 t\u1ea3 c\u00e1c m\u1ee9c logic 0 v\u00e0 1. Ngo\u00e0i m\u1ee9c \u0111i\u1ec7n \u00e1p ti\u00eau chu\u1ea9n c\u0169ng c\u1ed1 \u0111\u1ecbnh c\u00e1c gi\u00e1 tr\u1ecb tr\u1edf kh\u00e1ng t\u1ea3i \u0111\u01b0\u1ee3c \u0111\u1ea5u v\u00e0o bus c\u1ee7a b\u1ed9 ph\u1eadn v\u00e0 c\u00e1c tr\u1edf kh\u00e1ng ra c\u1ee7a b\u1ed9 ph\u00e1t.
\nM\u1ee9c \u0111i\u1ec7n \u00e1p c\u1ee7a ti\u00eau chu\u1ea9n RS232C ( chu\u1ea9n th\u01b0\u1eddng d\u00f9ng b\u00e2y gi\u1edd) \u0111\u01b0\u1ee3c m\u00f4 t\u1ea3 nh\u01b0 sau:
\n+ M\u1ee9c logic 0 : +3V , +12V
\n+ M\u1ee9c logic 1 : -12V, -3V
\nC\u00e1c m\u1ee9c \u0111i\u1ec7n \u00e1p trong ph\u1ea1m vi t\u1eeb -3V \u0111\u1ebfn 3V l\u00e0 tr\u1ea1ng th\u00e1i chuy\u1ec3n tuy\u1ebfn. Ch\u00ednh v\u00ec t\u1eeb – 3V t\u1edbi 3V l\u00e0 ph\u1ea1m vi kh\u00f4ng \u0111\u01b0\u1ee3c \u0111\u1ecbnh ngh\u0129a, trong tr\u01b0\u1eddng h\u1ee3p thay \u0111\u1ed5i gi\u00e1 tr\u1ecb logic t\u1eeb th\u1ea5p l\u00ean cao ho\u1eb7c t\u1eeb cao xu\u1ed1ng th\u1ea5p, m\u1ed9t t\u00edn hi\u1ec7u ph\u1ea3i v\u01b0\u1ee3t qua qu\u00e3ng qu\u00e1 \u0111\u1ed9 trong m\u1ed9t th\u01a1\u00ec gian ng\u1eafn h\u1ee3p l\u00fd. \u0110i\u1ec1u n\u00e0y d\u1eabn \u0111\u1ebfn vi\u1ec7c ph\u1ea3i h\u1ea1n ch\u1ebf v\u1ec1 \u0111i\u1ec7n dung c\u1ee7a c\u00e1c thi\u1ebft b\u1ecb tham gia v\u00e0 c\u1ee7a c\u1ea3 \u0111\u01b0\u1eddng truy\u1ec1n. T\u1ed1c \u0111\u1ed9 truy\u1ec1n d\u1eabn t\u1ed1i \u0111a ph\u1ee5 thu\u1ed9c v\u00e0o chi\u1ec1u d\u00e0i c\u1ee7a d\u00e2y d\u1eabn. \u0110a s\u1ed1 c\u00e1c h\u1ec7 th\u1ed1ng hi\u1ec7n nay ch\u1ec9 h\u1ed7 tr\u1ee3 v\u1edbi t\u1ed1c \u0111\u1ed9 19,2 kBd <\/p>\n

5. S\u01a1 \u0111\u1ed3 ch\u00e2n c\u1ed5ng Com 9 ch\u00e2n<\/strong>
\n\"\"<\/a>
\nCh\u1ee9c n\u0103ng c\u1ee7a c\u00e1c ch\u00e2n nh\u01b0 sau:
\n+ ch\u00e2n 1 : Data Carrier Detect (DCD) : Ph\u00e1t t\u00edn hi\u1ec7u mang d\u1eef li\u1ec7u
\n+ ch\u00e2n 2: Receive Data (RxD) : Nh\u1eadn d\u1eef li\u1ec7u
\n+ ch\u00e2n 3 : Transmit Data (TxD) : Truy\u1ec1n d\u1eef li\u1ec7u
\n+ ch\u00e2n 4 : Data Termial Ready (DTR) : \u0110\u1ea7u cu\u1ed1i d\u1eef li\u1ec7u s\u1eb5n s\u00e0ng \u0111\u01b0\u1ee3c k\u00edch ho\u1ea1t b\u1edfi b\u1ed9 ph\u1eadn khi mu\u1ed1n truy\u1ec1n d\u1eef li\u1ec7u
\n+ ch\u00e2n 5 : Singal Ground ( SG) : Mass c\u1ee7a t\u00edn hi\u1ec7u
\n+ ch\u00e2n 6 : Data Set Ready (DSR) : D\u1eef li\u1ec7u s\u1eb5n s\u00e0ng, \u0111\u01b0\u1ee3c k\u00edch ho\u1ea1t b\u1edfi b\u1ed9 truy\u1ec1n khi n\u00f3 s\u1eb5n s\u00e0ng nh\u1eadn d\u1eef li\u1ec7u
\n+ ch\u00e2n 7 : Request to Send : y\u00eau c\u1ea7u g\u1eedi,b\u00f4 truy\u1ec1n \u0111\u1eb7t \u0111\u01b0\u1eddng n\u00e0y l\u00ean m\u1ee9c ho\u1ea1t \u0111\u1ed9ng khi s\u1eb5n s\u00e0ng truy\u1ec1n d\u1eef li\u1ec7u
\n+ ch\u00e2n 8 : Clear To Send (CTS) : X\u00f3a \u0111\u1ec3 g\u1eedi ,b\u00f4 nh\u1eadn \u0111\u1eb7t \u0111\u01b0\u1eddng n\u00e0y l\u00ean m\u1ee9c k\u00edch ho\u1ea1t \u0111\u1ed9ng \u0111\u1ec3 th\u00f4ng b\u00e1o cho b\u1ed9 truy\u1ec1n l\u00e0 n\u00f3 s\u1eb5n s\u00e0ng nh\u1eadn t\u00edn hi\u1ec7u
\n+ ch\u00e2n 9 : Ring Indicate (RI) : B\u00e1o chu\u00f4ng cho bi\u1ebft l\u00e0 b\u1ed9 nh\u1eadn \u0111ang nh\u1eadn t\u00edn hi\u1ec7u rung chu\u00f4ng<\/p>\n

6. Qu\u00e1 tr\u00ecnh d\u1eef li\u1ec7u<\/strong>
\na) Qu\u00e1 tr\u00ecnh truy\u1ec1n d\u1eef li\u1ec7u
\nTruy\u1ec1n d\u1eef li\u1ec7u qua c\u1ed5ng n\u1ed1i ti\u1ebfp RS232 \u0111\u01b0\u1ee3c th\u1ef1c hi\u1ec7n kh\u00f4ng \u0111\u1ed3ng b\u1ed9. Do v\u1eady n\u00ean t\u1ea1i m\u1ed9t th\u1eddi \u0111i\u1ec3m ch\u1ec9 c\u00f3 m\u1ed9t bit \u0111\u01b0\u1ee3c truy\u1ec1n (1 k\u00ed t\u1ef1). B\u1ed9 truy\u1ec1n g\u1eedi m\u1ed9t bit b\u1eaft \u0111\u1ea7u (bit start) \u0111\u1ec3 th\u00f4ng b\u00e1o cho b\u1ed9 nh\u1eadn bi\u1ebft m\u1ed9t k\u00ed t\u1ef1 s\u1ebd \u0111\u01b0\u1ee3c g\u1eedi \u0111\u1ebfn trong l\u1ea7n truy\u1ec1n bit ti\u1ebfp the . Bit n\u00e0y lu\u00f4n b\u1eaft \u0111\u1ea7u b\u1eb1ng m\u1ee9c 0.. Ti\u1ebfp theo \u0111\u00f3 l\u00e0 c\u00e1c bit d\u1eef li\u1ec7u (bits data) \u0111\u01b0\u1ee3c g\u1eedi d\u01b0\u1edbi d\u1ea1ng m\u00e3 ASCII( c\u00f3 th\u1ec3 l\u00e0 5,6,7 hay 8 bit d\u1eef li\u1ec7u) Sau \u0111\u00f3 l\u00e0 m\u1ed9t Parity bit ( Ki\u1ec3m tra bit ch\u1eb5n, l\u1ebb hay kh\u00f4ng) v\u00e0 cu\u1ed1i c\u00f9ng l\u00e0 bit d\u1eebng – bit stop c\u00f3 th\u1ec3 l\u00e0 1, 1,5 hay 2 bit d\u1eebng.
\n\"\"<\/a>
\nb) T\u1ed1c \u0111\u1ed9 Baud
\n\u0110\u00e2y l\u00e0 m\u1ed9t tham s\u1ed1 \u0111\u1eb7c tr\u01b0ng c\u1ee7a RS232. Tham s\u1ed1 n\u00e0y ch\u00ednh l\u00e0 \u0111\u1eb7c tr\u01b0ng cho qu\u00e1 tr\u00ecnh truy\u1ec1n d\u1eef li\u1ec7u qua c\u1ed5ng n\u1ed1i ti\u1ebfp RS232 l\u00e0 t\u1ed1c \u0111\u1ed9 truy\u1ec1n nh\u1eadn d\u1eef li\u1ec7u hay c\u00f2n g\u1ecdi l\u00e0 t\u1ed1c \u0111\u1ed9 bit. T\u1ed1c \u0111\u1ed9 bit \u0111\u01b0\u1ee3c \u0111\u1ecbnh ngh\u0129a l\u00e0 s\u1ed1 bit truy\u1ec1n \u0111\u01b0\u1ee3c trong th\u1eddi gian 1 gi\u00e2y hay s\u1ed1 bit truy\u1ec1n \u0111\u01b0\u1ee3c trong th\u1eddi gian 1 gi\u00e2y. T\u1ed1c \u0111\u1ed9 bit n\u00e0y ph\u1ea3i \u0111\u01b0\u1ee3c thi\u1ebft l\u1eadp \u1edf b\u00ean ph\u00e1t v\u00e0 b\u00ean nh\u1eadn \u0111\u1ec1u ph\u1ea3i c\u00f3 t\u1ed1c \u0111\u1ed9 nh\u01b0 nhau ( T\u1ed1c \u0111\u1ed9 gi\u1eefa vi \u0111i\u1ec1u khi\u1ec3n v\u00e0 m\u00e1y t\u00ednh ph\u1ea3i chung nhau 1 t\u1ed1c \u0111\u1ed9 truy\u1ec1n bit)
\nNgo\u00e0i t\u1ed1c \u0111\u1ed9 bit c\u00f2n m\u1ed9t tham s\u1ed1 \u0111\u1ec3 m\u00f4 t\u1ea3 t\u1ed1c \u0111\u1ed9 truy\u1ec1n l\u00e0 t\u1ed1c \u0111\u1ed9 Baud. T\u1ed1c \u0111\u1ed9 Baud li\u00ean quan \u0111\u1ebfn t\u1ed1c \u0111\u1ed9 m\u00e0 ph\u1ea7n t\u1eed m\u00e3 h\u00f3a d\u1eef li\u1ec7u \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng \u0111\u1ec3 di\u1ec5n t\u1ea3 bit \u0111\u01b0\u1ee3c truy\u1ec1n c\u00f2n t\u00f4c \u0111\u1ed9 bit th\u00ec ph\u1ea3n \u00e1nh t\u1ed1c \u0111\u1ed9 th\u1ef1c t\u1ebf m\u00e0 c\u00e1c bit \u0111\u01b0\u1ee3c truy\u1ec1n.V\u00ec m\u1ed9t ph\u1ea7n t\u1eed b\u00e1o hi\u1ec7u s\u1ef1 m\u00e3 h\u00f3a m\u1ed9t bit n\u00ean khi \u0111\u00f3 hai t\u1ed1c \u0111\u1ed9 bit v\u00e0 t\u1ed1c \u0111\u1ed9 baud l\u00e0 ph\u1ea3i \u0111\u1ed3ng nh\u1ea5t
\nM\u1ed9t s\u1ed1 t\u1ed1c \u0111\u1ed9 Baud th\u01b0\u1eddng d\u00f9ng: 50, 75, 110, 150, 300, 600, 1200, 2400, 4800, 9600, 19200, 28800, 38400, 56000, 115200 \u2026 Trong thi\u1ebft b\u1ecb h\u1ecd th\u01b0\u1eddng d\u00f9ng t\u1ed1c \u0111\u1ed9 l\u00e0 19200
\nKhi s\u1eed d\u1ee5ng chu\u1ea9n n\u1ed1i ti\u1ebfp C\u00e1p c\u1ed5ng Com RS232 th\u00ec y\u00eau c\u1ea7u khi s\u1eed d\u1ee5ng chu\u1ea9n l\u00e0 th\u1eddi gian chuy\u1ec3n m\u1ee9c logic kh\u00f4ng v\u01b0\u1ee3t qu\u00e1 4% th\u1eddi gian truy\u1ec1n 1 bit. Do v\u1eady, n\u1ebfu t\u1ed1c \u0111\u1ed9 bit c\u00e0ng cao th\u00ec th\u1eddi gian truy\u1ec1n 1 bit c\u00e0ng nh\u1ecf th\u00ec th\u1eddi gian chuy\u1ec3n m\u1ee9c logic c\u00e0ng ph\u1ea3i nh\u1ecf. \u0110i\u1ec1u n\u00e0y l\u00e0m gi\u1edbi h\u1ea1n t\u1ed1c Baud v\u00e0 kho\u1ea3ng c\u00e1ch truy\u1ec1n.
\n\"\"<\/a>
\nc) Bit ch\u1eb5n l\u1ebb hay Parity bit
\n\u0110\u00e2y l\u00e0 bit ki\u1ec3m tra l\u1ed7i tr\u00ean \u0111\u01b0\u1eddng truy\u1ec1n. Th\u1ef1c ch\u1ea5t c\u1ee7a qu\u00e1 tr\u00ecnh ki\u1ec3m tra l\u1ed7i khi truy\u1ec1n d\u1eef li\u1ec7u l\u00e0 b\u1ed5 xung th\u00eam d\u1eef li\u1ec7u \u0111\u01b0\u1ee3c truy\u1ec1n \u0111\u1ec3 t\u00ecm ra ho\u1eb7c s\u1eeda m\u1ed9t s\u1ed1 l\u1ed7i trong qu\u00e1 tr\u00ecnh truy\u1ec1n . Do \u0111\u00f3 trong chu\u1ea9n RS232 s\u1eed d\u1ee5ng m\u1ed9t k\u1ef9 thu\u1eadt ki\u1ec3m tra ch\u1eb5n l\u1ebb.
\nM\u1ed9t bit ch\u1eb5n l\u1ebb \u0111\u01b0\u1ee3c b\u1ed5 sung v\u00e0o d\u1eef li\u1ec7u \u0111\u01b0\u1ee3c truy\u1ec1n \u0111\u1ec3 ch th\u1ea5y s\u1ed1 l\u01b0\u1ee3ng c\u00e1c bit “1” \u0111\u01b0\u1ee3c g\u1eedi trong m\u1ed9t khung truy\u1ec1n l\u00e0 ch\u1eb5n hay l\u1ebb.
\nM\u1ed9t Parity bit ch\u1ec9 c\u00f3 th\u1ec3 t\u00ecm ra m\u1ed9t s\u1ed1 l\u1ebb c\u00e1c l\u1ed7i ch\u1ea3 h\u1ea1n nh\u01b0 1,3,,5,7,9… N\u1ebfu nh\u01b0 m\u1ed9t bit ch\u1eb5n \u0111\u01b0\u1ee3c m\u1eafc l\u1ed7i th\u00ec Parity bit s\u1ebd tr\u00f9ng gi\u00e1 tr\u1ecb v\u1edbi tr\u01b0\u1eddng h\u1ee3p kh\u00f4ng m\u1eafc l\u1ed7i v\u00ec th\u1ebf kh\u00f4ng ph\u00e1t hi\u1ec7n ra l\u1ed7i. Do \u0111\u00f3 trong k\u1ef9 thu\u1eadt m\u00e3 h\u00f3a l\u1ed7i n\u00e0y kh\u00f4ng \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng trong tr\u01b0\u1eddng h\u1ee3p c\u00f3 kh\u1ea3 n\u0103ng m\u1ed9t v\u00e0i bit b\u1ecb m\u1eafc l\u1ed7i.
\n

\"\"<\/a>
Truy\u1ec1n nh\u1eadn k\u00fd t\u1ef1 "J" b\u1eb1ng RS232<\/figcaption><\/figure><\/p>\n","protected":false},"excerpt":{"rendered":"

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