DF-1 Protocol

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DF-1 / DF1 protocol is an asynchronous byte-oriented protocol that is used to communicate with most Allen Bradley RS232 interface modules. DF1 protocol consists of link layer and application layer formats. Link layer serial frame is a composition of conventional RS-232 serial frame with the parameters specified as 8 data bits, no parity, and a maximum baud rate of 19200. DF1 is ASCII character oriented protocol and works over half duplex and full duplex modes of communication.

Application Layer Messages[edit]

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[edit]


External links[edit]