{"id":747,"date":"2025-09-21T14:48:06","date_gmt":"2025-09-21T14:48:06","guid":{"rendered":"https:\/\/protolinker.com\/?post_type=docs&p=747"},"modified":"2025-09-23T09:55:24","modified_gmt":"2025-09-23T09:55:24","password":"","slug":"what-is-a-tag","status":"publish","type":"docs","link":"https:\/\/protolinker.com\/en\/documentation\/what-is-a-tag\/","title":{"rendered":"What is a Tag"},"content":{"rendered":"\n\n

A tag<\/strong> in Protolinker represents a specific piece of data<\/strong> exchanged through a protocol.<\/p>\n\n\n

In other words, while a protocol<\/strong> defines how devices talk<\/em>, a tag<\/strong> defines what information is being talked about<\/em>.<\/p>\n\n\n

For example, a temperature sensor connected via Modbus might have a tag called temperature, which holds the current reading in °C.<\/p>\n\n\n\n

\n\n\n

Why Tags Are Important<\/strong><\/h2>\n\n\n

Tags provide a consistent way to reference data across different protocols. Instead of remembering device addresses, register numbers, or message IDs, you work with clear, human-readable names.<\/p>\n\n\n

This makes complex integrations much easier to manage, since you can:<\/p>\n\n\n

    \n
  • \nIdentify values<\/strong> by meaningful names (e.g., motor_speed instead of register 40001).<\/li>\n\n\n\n
  • \nLink protocols<\/strong> together by mapping tags from one protocol to another.<\/li>\n\n\n\n
  • \nMonitor and debug<\/strong> data flow in a way that is understandable without deep protocol knowledge.<\/li>\n<\/ul>\n\n\n\n
    \n\n\n

    How Tags Work in Protolinker<\/strong><\/h2>\n\n\n
      \n
    1. \nTag Creation<\/strong>
        \n
      • Tags are created inside Protolinker by defining a name (e.g., temperature), data type (e.g., float), and source (e.g., a Modbus register).<\/li>\n<\/ul>\n<\/li>\n\n\n\n
      • \nTag Linking<\/strong>
          \n
        • Once defined, tags can be linked between different protocols.<\/li>\n\n\n\n
        • For example: A Modbus tag temperature can be linked to an MQTT tag sensor\/temperature, making the data from the Modbus sensor available to the MQTT topic and vice versa.<\/li>\n<\/ul>\n<\/li>\n\n\n\n
        • \nTag Transformation (Optional)<\/strong>
            \n
          • Protolinker supports applying simple transformations to tags using scripts.<\/li>\n\n\n\n
          • This is useful when you need to scale, convert, or filter the data before forwarding it.<\/li>\n<\/ul>\n<\/li>\n\n\n\n
          • \nTag Usage<\/strong>
              \n
            • Applications or external systems connected to Protolinker will only “see” or “publish” the tags, not the raw protocol addresses.<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n\n\n\n
              \n\n\n

              Example<\/strong><\/h2>\n\n\n
                \n
              • \nDevice side:<\/strong> Modbus sensor reports register 40001 = 253 (raw value).<\/li>\n\n\n\n
              • \nProtolinker tag:<\/strong> temperature = 25.3 °C (scaled).<\/li>\n\n\n\n
              • \nOutput side:<\/strong> Published via MQTT as sensor\/temperature = 25.3.<\/li>\n<\/ul>\n\n\n

                This way, tags act as the bridge between raw protocol data and meaningful, usable information<\/strong>.<\/p>\n","protected":false},"excerpt":{"rendered":"

                A tag in Protolinker represents a specific piece of data exchanged through a protocol. In other words, while a protocol defines how devices talk, a tag defines what information is being talked about. For example, a temperature sensor connected via Modbus might have a tag called temperature, which holds the current reading in °C. Why …<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"doc_category":[15],"doc_tag":[],"class_list":["post-747","docs","type-docs","status-publish","hentry","doc_category-tags"],"year_month":"2026-07","word_count":292,"total_views":0,"reactions":{"happy":0,"normal":0,"sad":0},"author_info":{"name":"beraldoigor","author_nicename":"beraldoigor","author_url":"https:\/\/protolinker.com\/en\/author\/beraldoigor\/"},"doc_category_info":[{"term_name":"Tags","term_url":"https:\/\/protolinker.com\/en\/docs-category\/tags\/"}],"doc_tag_info":[],"_links":{"self":[{"href":"https:\/\/protolinker.com\/en\/wp-json\/wp\/v2\/docs\/747","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/protolinker.com\/en\/wp-json\/wp\/v2\/docs"}],"about":[{"href":"https:\/\/protolinker.com\/en\/wp-json\/wp\/v2\/types\/docs"}],"author":[{"embeddable":true,"href":"https:\/\/protolinker.com\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/protolinker.com\/en\/wp-json\/wp\/v2\/comments?post=747"}],"version-history":[{"count":0,"href":"https:\/\/protolinker.com\/en\/wp-json\/wp\/v2\/docs\/747\/revisions"}],"wp:attachment":[{"href":"https:\/\/protolinker.com\/en\/wp-json\/wp\/v2\/media?parent=747"}],"wp:term":[{"taxonomy":"doc_category","embeddable":true,"href":"https:\/\/protolinker.com\/en\/wp-json\/wp\/v2\/doc_category?post=747"},{"taxonomy":"doc_tag","embeddable":true,"href":"https:\/\/protolinker.com\/en\/wp-json\/wp\/v2\/doc_tag?post=747"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}