DF-1 Protocol

DF-1 / DF1 protocol is an asynchronous byte-oriented protocol that is used to communicate with most Allen Bradley RS-232 interface modules. DF1 protocol consists of link layer and application layer formats. DF1 works over half duplex and full duplex modes of communication.

Application layer messages

Application layer message format consists of Command Initiator messages (request messages) and Command Executor (reply messages). Important command initiator messages are as follows.

  • apply port configuration
  • bit write
  • change mode
  • close file
  • diagnostic status
  • disable forces
  • disable outputs
  • download request
  • echo
  • enable outputs
  • enable PLC scanning
  • enter download mode
  • enter upload mode
  • exit download/upload mode
  • file read
  • file write
  • get edit resource
  • initialize memory
  • modify PLC-2 compatibility file
  • open file
  • physical read
  • physical write
  • read bytes physical
  • read diagnostic counters
  • reset diagnostic counters
  • read link parameters
  • read-modify-write
  • read section size
  • restart request
  • set CPU mode
  • set data table size
  • set ENQs
  • set link parameters
  • set NAKs
  • set timeout
  • set variables
  • shutdown

See also
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