rs232 = require("luars232")

-- Linux
-- port_name = "/dev/ttyS0"

-- Windows
port_name = "COM1"

local out = io.stderr

-- open port
local e, p = rs232.open(port_name)
if e ~= rs232.RS232_ERR_NOERROR then
	-- handle error
	out:write(string.format("can't open serial port '%s', error: '%s'\n",
			port_name, rs232.error_tostring(e)))
	return
end

-- set port settings
assert(p:set_baud_rate(rs232.RS232_BAUD_115200) == rs232.RS232_ERR_NOERROR)
assert(p:set_data_bits(rs232.RS232_DATA_8) == rs232.RS232_ERR_NOERROR)
assert(p:set_parity(rs232.RS232_PARITY_NONE) == rs232.RS232_ERR_NOERROR)
assert(p:set_stop_bits(rs232.RS232_STOP_1) == rs232.RS232_ERR_NOERROR)
assert(p:set_flow_control(rs232.RS232_FLOW_OFF)  == rs232.RS232_ERR_NOERROR)

out:write(string.format("OK, port open with values '%s'\n", tostring(p)))

-- read with timeout
local read_len = 1 -- read one byte
local timeout = 100 -- in miliseconds
local err, data_read, size = p:read(read_len, timeout)
assert(e == rs232.RS232_ERR_NOERROR)
			
-- write without timeout
err, len_written = p:write("test")
assert(e == rs232.RS232_ERR_NOERROR)

-- write with timeout 100 msec
err, len_written = p:write("test\n", timeout)
assert(e == rs232.RS232_ERR_NOERROR)

-- close
assert(p:close() == rs232.RS232_ERR_NOERROR)