{"id":37942,"date":"2024-01-30T21:14:49","date_gmt":"2024-01-30T21:14:49","guid":{"rendered":"https:\/\/www.alicat.com\/?post_type=article&#038;p=37942"},"modified":"2026-03-12T17:54:59","modified_gmt":"2026-03-12T17:54:59","slug":"rs-232-kommunikation-mit-einem-alicat","status":"publish","type":"support","link":"https:\/\/www.alicat.com\/de\/support\/rs-232-communication-with-an-alicat\/","title":{"rendered":"RS-232-Kommunikation mit einem Alicat"},"content":{"rendered":"\n[et_pb_section fb_built=&#8221;1&#8243; _builder_version=&#8221;4.24.2&#8243; _module_preset=&#8221;default&#8221; custom_css_free_form=&#8221;@media (max-width: 375px) {||  .et-db #et-boc .et-l .et_pb_post_content_0_tb_body {||  width:100% !important;||  }}&#8221; global_colors_info=&#8221;{}&#8221; theme_builder_area=&#8221;post_content&#8221;][et_pb_row _builder_version=&#8221;4.23.1&#8243; _module_preset=&#8221;default&#8221; global_colors_info=&#8221;{}&#8221; theme_builder_area=&#8221;post_content&#8221;][et_pb_column type=&#8221;4_4&#8243; _builder_version=&#8221;4.23.1&#8243; _module_preset=&#8221;default&#8221; global_colors_info=&#8221;{}&#8221; theme_builder_area=&#8221;post_content&#8221;][et_pb_heading title=&#8221;RS-232 communication with an Alicat&#8221; _builder_version=&#8221;4.23.1&#8243; _module_preset=&#8221;default&#8221; global_colors_info=&#8221;{}&#8221; theme_builder_area=&#8221;post_content&#8221;][\/et_pb_heading][et_pb_text _builder_version=&#8221;4.27.4&#8243; _module_preset=&#8221;default&#8221; hover_enabled=&#8221;0&#8243; global_colors_info=&#8221;{}&#8221; theme_builder_area=&#8221;post_content&#8221; sticky_enabled=&#8221;0&#8243;]<div class=\"link-with-icons-wrap m-b\"><strong><a href=\"https:\/\/www.alicat.com\/support\/serial-communication-tutorial\/\">Serial communication tutorial\u00a0<\/a><\/strong><\/div>\n<div class=\"link-with-icons-wrap m-b\"><\/div>\nThe RS-232 protocol is the default method of talking to Alicat devices. While instruments can also be configured using a variety of other protocols (RS-485, PROFIBUS, EtherCAT<sup>&reg;<\/sup>, Modbus RTU or TCP\/IP, DeviceNet, PROFINET, and EtherNet\/IP), the tried and true RS-232 communication standard remains the go-to method for commanding and reading Alicats.\n<h2>The not-so-standard RS-232 standard<\/h2>\nThe RS-232 protocol was originally introduced over 50 years ago, in 1960. The primary reason RS-232 has survived so long is that it is a useful, low level, rudimentary signal with fairly loose operational guidelines.\n<p class=\"nitro-offscreen nitro-lazy-render\">In 1962, the sole application for the RS-232 communication standard was connecting electromechanical typewriters and their host mainframes\/modems, commonly known as \u2018Teletype\u2019 systems. When more advanced electronic machines were subsequently developed, proprietary adaptations led to nonstandard pin assignments, connectors, and signal voltage levels. For example, the original specification called for a DB-15 connector, but in the last 30 years most RS-232 products have adopted a DB-9 connector (technically called DE-9M) instead.<\/p>\n\n<h3 class=\"nitro-offscreen nitro-lazy-render\">How does it work?<\/h3>\n<p class=\"nitro-offscreen nitro-lazy-render\">The data being sent on RS-232 lines simply consists of positive (+) and negative (-) voltage pulses relative to a ground reference. A group of +\/- pulses sent by one device is carefully timed by the receiving device, where it is then decoded using the connected hardware.<\/p>\n<p class=\"nitro-offscreen nitro-lazy-render\"><span>The RS-232 protocol is not used for character encoding, spacing, start bits, stop bits, bit order, error detection, bit transmission rate, etc. Rather, they are established by the user\u2019s connected circuitry. This is usually in the form of a serial communication port and its associated chips and transistors.\u00a0<\/span><\/p>\n<p class=\"nitro-offscreen nitro-lazy-render\">The COM port makes sense of the pulses on behalf of the attached computer or peripheral. For reference, an RS-232 system must transmit from one device (sent on its Tx pin) to a receiving device (received on its Rx pin), and vice-versa. It is worth noting that in an RS-232 three wire system, you should not connect Tx to Tx or Rx to Rx.<\/p>\n<p class=\"nitro-offscreen nitro-lazy-render\">The only pin that is connected directly is the ground pin, which gives both ends a common reference point from which to measure the pulses. Each RS-232 driver uses inversion logic and employs a single-ended, bi-polar output voltage to feed to a UART (Universal Asynchronous Receiver\/Transmitter). Because the system has three wires and two distinct channels of communication, it is considered a \u2018full duplex\u2019 system. Data can be transmitted at the same time it is being received.<\/p>\n\n<h2 class=\"nitro-offscreen nitro-lazy-render\">How Alicat uses RS-232<\/h2>\n<p class=\"nitro-offscreen nitro-lazy-render\">The RS-232 \u2018standard\u2019 is fairly loose, so how does Alicat use it? In addition to the ubiquitous DB-9 and the \u2018standard\u2019 DB-15 connector, Alicat can provide RS-232 communication on any offered connector. This includes DB-15, 6 pin industrial locking connectors, and the default 8 pin miniDIN jack.<\/p>\n\n<h3 class=\"nitro-offscreen nitro-lazy-render\">Bending the rules for signal level and polarity<\/h3>\n<span>The real departure from the standard is found in how Alicat has exploited signal levels, enabling multiple units to work on the same COM port. Because Alicat devices do not produce negative voltages, a traditional +\/- 15 V RS-232 is not possible. Fortunately, a positive-only pulse of +5 V can be made to replicate an RS-232 waveform (logic high \u2018mark\u2019 vs. logic low \u2018space\u2019), readable by 99% of all UARTs used today.\u00a0<\/span>\n<p class=\"nitro-offscreen nitro-lazy-render\">UART serial ports are no longer used and have been replaced by USB to serial converters. Today, the FTDI chipset is commonly used to replicate the COM port. Alicat\u2019s unique signal profile is also fully compatible with these devices.<\/p>\n\n<h3 class=\"nitro-offscreen nitro-lazy-render\">Using up to 26 units on a single serial COM port<\/h3>\n<p class=\"nitro-offscreen nitro-lazy-render\">Alicat has also designed a workaround enabling up to 26 units to be used at once on a single serial COM Port. The technical term for this capability is \u2018multi-drop\u2019 communication, and it is supported by all Alicat units equipped with serial communication (RS-232 or RS-485).<\/p>\n<p class=\"nitro-offscreen nitro-lazy-render\">Through multi-drop communication, every device on the line is configured to have a unique identifying letter (A-Z), and every unit listens to the commands that have been sent. Even though every device listens to the commands, a unit will only accept and respond if the instruction begins with that device\u2019s unique ID letter. This means you can connect three flow controllers on the same three wires (electrically in parallel), and then read the current flow rate on unit \u2018A\u2019, give a new setpoint to \u2018B\u2019, <em>and<\/em> reset the totalizer on \u2018C\u2019.<\/p>\n\n<h2 class=\"nitro-offscreen nitro-lazy-render\">Conclusion<\/h2>\n<p class=\"nitro-offscreen nitro-lazy-render\">Even though the RS-232 communication \u2018standard\u2019 is old enough for a place in the Smithsonian Institution, it is still heavily used for all types of computer-based systems that need to talk to various peripheral components. Employing the universal ASCII (American Standard Code for Information Interchange) character set as our language, Alicat instruments will continue to be sold with the robust, universal, and reliable RS-232 system for the foreseeable future.<\/p>[\/et_pb_text][\/et_pb_column][\/et_pb_row][\/et_pb_section]\n","protected":false},"featured_media":46458,"parent":0,"template":"","meta":{"_acf_changed":false,"_et_pb_use_builder":"on","_et_pb_old_content":"","_et_gb_content_width":"1920","content-type":"","_searchwp_excluded":""},"categories":[],"class_list":["post-37942","support","type-support","status-publish","has-post-thumbnail","hentry"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO Premium plugin v27.6 (Yoast SEO v27.6) - https:\/\/yoast.com\/product\/yoast-seo-premium-wordpress\/ -->\n<title>RS-232 Communication with an Alicat - Alicat Scientific<\/title>\n<meta name=\"description\" content=\"The RS-232 protocol is the default method of talking to Alicat devices. While instruments can also be configured using a variety of other protocols (RS-485, PROFIBUS, EtherCAT, Modbus RTU or TCP\/IP, DeviceNet, PROFINET, and EtherNet\/IP), the tried and true RS-232 communication standard remains the go-to method for commanding and reading Alicats.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.alicat.com\/de\/unterstutzung\/rs-232-kommunikation-mit-einem-alicat\/\" \/>\n<meta property=\"og:locale\" content=\"de_DE\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"RS-232 Communication with an Alicat\" \/>\n<meta property=\"og:description\" content=\"The RS-232 protocol is the default method of talking to Alicat devices. 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