{"id":41377,"date":"2024-05-21T13:45:00","date_gmt":"2024-05-21T13:45:00","guid":{"rendered":"https:\/\/www.alicat.com\/?post_type=document&#038;p=41377"},"modified":"2026-02-19T17:25:56","modified_gmt":"2026-02-19T17:25:56","slug":"faq-modbus","status":"publish","type":"document","link":"https:\/\/www.alicat.com\/de\/documentation\/faq-modbus\/","title":{"rendered":"Modbus-FAQ"},"content":{"rendered":"\n[et_pb_section fb_built=&#8221;1&#8243; _builder_version=&#8221;4.27.5&#8243; _module_preset=&#8221;default&#8221; hover_enabled=&#8221;0&#8243; 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; locked=&#8221;off&#8221; global_colors_info=&#8221;{}&#8221; custom_padding=&#8221;0px|4vw|0px|4vw|true|true&#8221; sticky_enabled=&#8221;0&#8243;][et_pb_row _builder_version=&#8221;4.27.5&#8243; _module_preset=&#8221;default&#8221; hover_enabled=&#8221;0&#8243; global_colors_info=&#8221;{}&#8221; custom_padding=&#8221;0px||||false|false&#8221; sticky_enabled=&#8221;0&#8243;][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;][et_pb_heading title=&#8221;Modbus FAQ&#8221; _builder_version=&#8221;4.24.3&#8243; _module_preset=&#8221;default&#8221; global_colors_info=&#8221;{}&#8221;][\/et_pb_heading][et_pb_text _builder_version=&#8221;4.27.5&#8243; _module_preset=&#8221;default&#8221; hover_enabled=&#8221;0&#8243; global_colors_info=&#8221;{}&#8221; sticky_enabled=&#8221;0&#8243;]Alicat devices are compatible with a variety of analog, serial, or industrial\u00a0<a href=\"https:\/\/www.alicat.com\/support\/communication-options-for-alicat-instruments\/\">communication protocols<\/a>\u00a0for easy data collection and analysis. Options include analog (4-20 mA, 0-10 Vdc, 0-5 Vdc, or 1-5 Vdc), ASCII and Modbus RTU over RS-232, ASCII and Modbus RTU over RS-485, Profibus, DeviceNet, EtherNet\/IP, Modbus TCP\/IP, and EtherCAT<sup>\u00ae<\/sup>.\n\nIn this article, we provide answers to common questions about Modbus.\n\n<a href=\"https:\/\/documents.alicat.com\/manuals\/DOC-MANUAL-MODBUS.pdf\" target=\"_blank\" rel=\"noopener\">Modbus manual<\/a>[\/et_pb_text][et_pb_accordion _builder_version=&#8221;4.27.5&#8243; _module_preset=&#8221;default&#8221; toggle_font=&#8221;|700|||||||&#8221; hover_enabled=&#8221;0&#8243; global_colors_info=&#8221;{}&#8221; custom_margin=&#8221;1rem||||false|false&#8221; sticky_enabled=&#8221;0&#8243;][et_pb_accordion_item title=&#8221;Hidden Item So All Items Are Closed on Page Load&#8221; _builder_version=&#8221;4.27.5&#8243; _module_preset=&#8221;default&#8221; custom_css_free_form=&#8221;selector {||  display: none;||}&#8221; hover_enabled=&#8221;0&#8243; sticky_enabled=&#8221;0&#8243;][\/et_pb_accordion_item][et_pb_accordion_item title=&#8221;Where can I find supporting download files?&#8221; open=&#8221;on&#8221; _builder_version=&#8221;4.24.3&#8243; _module_preset=&#8221;default&#8221; global_colors_info=&#8221;{}&#8221;]<div class=\"su-spoiler su-spoiler-style-fancy su-spoiler-icon-chevron\" data-scroll-offset=\"0\" data-anchor-in-url=\"no\">\n<div class=\"su-spoiler-content su-u-clearfix su-u-trim\">\n<p>Find supporting downloads such as MBP files <a href=\"https:\/\/www.alicat.com\/support\/communication-options-for-alicat-instruments\/\" target=\"_blank\" rel=\"noopener\">here<\/a>.<\/p>\n<\/div>\n<\/div>\n<div class=\"su-spoiler su-spoiler-style-fancy su-spoiler-icon-chevron su-spoiler-closed\" data-scroll-offset=\"0\" data-anchor-in-url=\"no\">\n<div class=\"su-spoiler-title\" role=\"button\" tabindex=\"0\"><\/div>\n<\/div>[\/et_pb_accordion_item][et_pb_accordion_item title=&#8221;Which products can have Modbus installed?&#8221; _builder_version=&#8221;4.27.4&#8243; _module_preset=&#8221;default&#8221; global_colors_info=&#8221;{}&#8221; open=&#8221;off&#8221;]<ul>\n\t<li><strong>Modbus RTU<\/strong> is available on all Alicat products.<\/li>\n\t<li><strong>Modbus TCP\/IP<\/strong> available on most product, with the exception of:\n<ul>\n\t<li>OEM devices (<a href=\"https:\/\/www.alicat.com\/products\/gas-flow\/mass-flow-controller\/small-thermal-mass-flow-controllers\/\">BC<\/a>,\u00a0<a href=\"https:\/\/www.alicat.com\/products\/pressure\/pressure-controller\/small-pressure-controllers-oem\/\">EPC, and\u00a0EPCD<\/a>-Series)<\/li>\n\t<li>Portable instruments (<a href=\"https:\/\/www.alicat.com\/products\/gas-flow\/mass-flow-meter\/portable-mass-flow-meters\/\">MB<\/a>, <a href=\"https:\/\/www.alicat.com\/products\/pressure\/pressure-meter\/portable-pressure-meters\/\">PB<\/a>, and <a href=\"https:\/\/www.alicat.com\/products\/liquid-flow\/liquid-flow-meter\/portable-liquid-meters\/\">LB<\/a>-Series)<\/li>\n\t<li><a href=\"https:\/\/www.alicat.com\/documentation\/csa-atex-certifications-for-hazardous-environments\/\">Class 1 Division 2<\/a>\u00a0area instruments (-X part numbers)<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<div class=\"link-with-icons-wrap m-b\"><a href=\"https:\/\/www.alicat.com\/support\/communication-options-for-alicat-instruments\/\" target=\"_blank\" rel=\"noopener\">Communications protocols comparison<\/a><\/div>[\/et_pb_accordion_item][et_pb_accordion_item title=&#8221;What are the differences between Modbus RTU and Modbus TCP\/IP?&#8221; _builder_version=&#8221;4.24.3&#8243; _module_preset=&#8221;default&#8221; global_colors_info=&#8221;{}&#8221; open=&#8221;off&#8221;]<ul>\n<li><strong>Modbus RTU<\/strong> is a master\/slave based serial protocol using standard serial communication interfaces such as RS-232 or RS-485.<\/li>\n<li><strong>Modbus TCP\/IP<\/strong> uses the same command set as Modbus RTU. Instead of serial cables, the TCP\/IP protocol uses off-the-shelf network hardware to carry messages.<\/li>\n<\/ul>[\/et_pb_accordion_item][et_pb_accordion_item title=&#8221;How does Modbus change instrument specifications?&#8221; _builder_version=&#8221;4.24.3&#8243; _module_preset=&#8221;default&#8221; global_colors_info=&#8221;{}&#8221; open=&#8221;off&#8221;]<p><strong>Modbus RTU<\/strong> operates in parallel to our standard serial interface, and does not change any specifications.<\/p>\n<p><strong>Modbus TCP\/IP\u00a0<\/strong>has the following changes:<\/p>\n<ul>\n<li><strong>Alicat part number:\u00a0<\/strong>-MODTCPIP<\/li>\n<li><strong>Analog signals?:\u00a0<\/strong>No<\/li>\n<li><strong>Electrical connections:<\/strong> Comms over dual RJ45<\/li>\n<li><strong>Additional power requirement:\u00a0<\/strong>120 mA<\/li>\n<li><strong>Software compatibility:\u00a0<\/strong><a href=\"https:\/\/www.alicat.com\/documentation\/labview-virtual-instrument-drivers\/\">LabVIEW<\/a>; Modbus Poll<\/li>\n<li><strong>Max number of devices on network:\u00a0<\/strong>No limit<\/li>\n<\/ul>\n<div class=\"link-with-icons-wrap m-b\"><a href=\"https:\/\/www.alicat.com\/technical-reference\/#pinouts\" target=\"_blank\" rel=\"noopener\">Alicat connector pinout diagrams<\/a><\/div>[\/et_pb_accordion_item][et_pb_accordion_item title=&#8221;Do I still have a choice of gases and gas mixes on Modbus instruments?&#8221; _builder_version=&#8221;4.24.3&#8243; _module_preset=&#8221;default&#8221; global_colors_info=&#8221;{}&#8221; open=&#8221;off&#8221;]<div class=\"et_pb_toggle et_pb_module et_pb_accordion_item et_pb_accordion_item_4 et_pb_toggle_open\">\n<div class=\"et_pb_toggle_content clearfix\">\n<p><span>Yes. Gas instruments with EtherCAT have the full\u00a0<\/span><a href=\"https:\/\/www.alicat.com\/documentation\/gas-select-gas-list\/\" target=\"_blank\" rel=\"noopener\">Gas Select\u2122 list<\/a><span>\u00a0of gas calibrations and\u00a0<\/span><a href=\"https:\/\/www.alicat.com\/support\/gas-select-composer-gas-mix-calibration\/\" target=\"_blank\" rel=\"noopener\">Composer\u2122 gas mixing firmware<\/a><\/p>\n<\/div>\n<\/div>\n<div class=\"et_pb_toggle et_pb_module et_pb_accordion_item et_pb_accordion_item_5  et_pb_toggle_close\"><\/div>[\/et_pb_accordion_item][et_pb_accordion_item title=&#8221;Can I retrofit Modbus to my existing Alicat devices?&#8221; _builder_version=&#8221;4.24.3&#8243; _module_preset=&#8221;default&#8221; global_colors_info=&#8221;{}&#8221; open=&#8221;off&#8221;]<ul>\n<li>Newer Alicat devices with a serial communications interface can be updated to support Modbus-RTU.<\/li>\n<li>Alicat devices with an Ethernet adapter card such as existing EtherNet\/IP or EtherCAT card with 9v or earlier firmware can be reconfigured to support Modbus TCP\/IP.<\/li>\n<\/ul>[\/et_pb_accordion_item][et_pb_accordion_item title=&#8221;What control systems or software does Alicat recommend for controlling a Modbus device?&#8221; _builder_version=&#8221;4.24.3&#8243; _module_preset=&#8221;default&#8221; global_colors_info=&#8221;{}&#8221; open=&#8221;off&#8221;]<p>There are many options for building Modbus controls, making it challenging to make a single recommendation.<\/p>\n<ul>\n<li>Modbus Poll is a good testing and simulation tool for early validation and learning the Modbus protocol.<\/li>\n<li>If you have Python experience, <a href=\"https:\/\/github.com\/riptideio\/pymodbus\" target=\"_blank\" rel=\"noopener\">PyModbus<\/a> is well documented and flexible solution for building custom Modbus systems.<\/li>\n<li>If you are looking for dedicated hardware to control your application, you have many options as virtually any PLC will support Modbus. Automation Direct has affordable PLC and HMI solutions, and Schneider electric could be considered the reference implementation for Modbus devices.<\/li>\n<li><a href=\"https:\/\/www.vtscada.com\/\" target=\"_blank\" rel=\"noopener\">VTScada<\/a> is a commercial solution which provides good tools for building control interfaces and GUIs. It offers a security layer for remote\/internet based controls and an excellent free demo so you can try it before you commit to a full software suite.<\/li>\n<\/ul>[\/et_pb_accordion_item][et_pb_accordion_item title=&#8221;How fast are communications with an Alicat instrument equipped with Modbus?&#8221; _builder_version=&#8221;4.24.3&#8243; _module_preset=&#8221;default&#8221; global_colors_info=&#8221;{}&#8221; open=&#8221;off&#8221;]<ul>\n<li><strong>Modbus RTU\u2019s<\/strong> speed is limited by the speed of the serial bus, ranging from 40 Hz at 19200 baud up to 200 Hz at 115200 baud.<\/li>\n<li><strong>Modbus TCP\/IP<\/strong> operates at approximately 50 Hz.<\/li>\n<\/ul>[\/et_pb_accordion_item][\/et_pb_accordion][\/et_pb_column][\/et_pb_row][\/et_pb_section]\n","protected":false},"featured_media":0,"parent":0,"template":"","meta":{"_acf_changed":false,"_et_pb_use_builder":"on","_et_pb_old_content":"","_et_gb_content_width":"1400","content-type":"","_searchwp_excluded":""},"categories":[],"class_list":["post-41377","document","type-document","status-publish","hentry"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO Premium plugin v27.3 (Yoast SEO v27.3) - 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