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eip

EtherNet/IP client for reading data files from Allen-Bradley style PLCs.

Available on: Flexs Q5C Flexs Q5 Pro Flexs Q5M

The eip object speaks EtherNet/IP in both directions:

  • Client — eip.connect() / eip.read() read PLC data files. Files are addressed by a type prefix and number — F, O, I, S, B, T, R, N depending on type (e.g. "F103" for float file 103). Returned data is a packed binary buffer parsed with the bin reader functions.
  • Server — eip.handle() answers incoming EtherNet/IP read and write requests from a PLC, letting the device appear as a data file the PLC polls and commands directly.

Functions

eip.connect() 

eip.connect(ip) → number

Connects to a PLC over EtherNet/IP.

Arguments

NameTypeRequiredDefaultDescription
ip string yes — PLC IP address, e.g. "192.168.168.1".

Returns

number 0 = connected, otherwise an error code.

Example

if(eip.connect("192.168.168.1") === 0){
  // read files ...
  eip.disconnect();
} else {
  print("PLC Connection Failed");
}

eip.read() 

eip.read(file, offset, bytes) → { status, data }

Reads bytes from a PLC data file.

Reads bytes starting at element offset of the addressed file. Parse the returned buffer with string.seek() and string.read().

Arguments

NameTypeRequiredDefaultDescription
file string yes — File address with type prefix (F,O,I,S,B,T,R,N) + number, e.g. "F103".
offset number yes — Starting element offset within the file.
bytes number yes — Number of bytes to read, e.g. 4*4 for four 32-bit floats.

Returns

object { status, data } — status 0 = success; data is a bin buffer.

Example

let res = eip.read("F103", 1, 4*4); // four 4-byte floats

if(res.status === 0){
  res.data.seek(0); // Position our cursor at the start of the data
  let plc = {
    flow:      res.data.read("F32ABCD"),
    pressure:  res.data.read(), // No format specified, use the last specified format
    pumpSpeed: res.data.read(),
    temp:      res.data.read(),
    lastUpdated: now()
  };
  print(string(plc));
} else {
  print("PLC Read Failed");
}

eip.handle() 

eip.handle(handler)

Answers incoming EtherNet/IP read and write requests from a PLC.

Registers a handler for EtherNet/IP requests arriving at the device. The request object provides:

Field Meaning
req.file The requested file address (e.g. "F103").
req.bytes Read requests: the byte length of the requested data.
req.data Write requests: a bin buffer with the written data. Absent on reads.

Write requests (req.data present): parse the buffer with req.data.seek() / req.data.read() and apply the values — e.g. unpack a PLC status word into individual io flags with bit masks.

Read requests: build a response with bin.alloc() and the buffer write methods (including the "BIT" format for packing status bits), then return the buffer.

Arguments

NameTypeRequiredDefaultDescription
handler function yes — Callback function(req){ … } — return a bin buffer to answer read requests.

Example

eip.handle(function(req){          // handle incoming EtherNet/IP requests
  if(req.data){                    // write request
    req.data.seek(0);
    let status = req.data.read("U16AB");
    io.PALL = {
      feedEnable:  status & 1,
      masterAlarm: (status & (1<<5)) > 0,
      flowAvailable: req.data.read("U16AB") / 0.2777778
    };
  } else {                         // read request — build and return a reply
    let buff = bin.alloc(100);
    buff.write("BIT", [0, io.p304.running, io.p303.running, 0,0,0,0,0, 0,0,0,0,0,0,0,0]);
    buff.write("U16AB", [151.2 * 0.2777778, io.clearwellLevel701.inst * 10]);
    return buff;
  }
});

eip.disconnect() 

eip.disconnect()

Ends the EtherNet/IP connection.

Example

eip.disconnect();