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Address Commands to Specific RS-485 Devices

Updated Aug 14, 2025

Reported In

Hardware

  • RS-422/RS-485

Issue Details

  • If RS-485 can have up to 32 devices connected to a network, how does my RS-485 port specify which device will get each command?
  • How can I ensure that a specific RS-485 device on my network receives a command?
  • I have multiple RS-485 devices on my network. How can I send a command to all devices or a subset of devices?
     

Solution

Commands on a RS-485 bus are preceded by an address ID, usually 1 byte. All devices on the bus will receive commands sent to the bus and if a device is not programmed to respond to a particular ID, it will ignore the command. 

To determine the address IDs and commands that your instrument responds to, refer to your instrument's user manual.

Additional Information

Devices may also accept multiple IDs. For example, instead of configuring 32 sensors individually, one can send the configuration string with a global ID and configure them all at once. To access the sensors individually, the devices can be referenced with their specific IDs.

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