ESPA 4.4.4

[admin]

Here's a short example script that can be used to poll slave nr 2. It does not send ack/nack and does not parse the message but can be used a starting point to check the communication. Change serial port name and parameters as needed.

Code:

EOT = string.char(4)
ENQ = string.char(5)

function poll(addr)
  port:flush()
  port:write(addr .. ENQ)

  local buf = {}

  while true do
    local ch, err = port:read(1, 1)

    if ch then
      if ch == EOT then
        break
      else
        buf[ #buf + 1 ] = ch
      end
    else
      return nil, err
    end
  end

  return table.concat(buf)
end

port = require('serial').open('/dev/RS232', { baudrate = 9600 })
res, err = poll(2)

loghex(res, err)