(22.12.2021, 08:00)admin Wrote: Can you describe your task in more detail? Protocol description would be helpful as well.
The main rule with serial ports is that only a single script can access the port. For reading you can set read length to -1 to skip waiting and read only the data that is already buffered by the driver.
Good afternoon. I need to constantly poll the room presence sensors through the rs232 port, on average, all sensors are polled once every 2.5 seconds. I transfer the result of the survey to group addresses. My script is hovering at the bottom
Code:
if not port then
require('serial')
port, err = serial.open('/dev/RS232', {baudrate = 38400, databits = 8, stopbits = 1, parity = 'none', duplex = 'full'})
if port then
port:flush()
else
log('Error open port in: ' .. err)
end
end
function readline(port, timeout)
local char, buf
buf = {}
while true do
char = port:read(1, timeout or 0.2)
if char == nil or char == '\n' then
break
elseif char ~= '\r' then
table.insert(buf, char)
end
end
return table.concat(buf)
end
function writetoport(port, timeout, command)
port:write(command)
line = readline(port, timeout)
if #line > 0 then
return line
else
return "No reply received"
end
end
function str2hex(str)
raw_len = string.len(str)
i = 1
value = ''
while i <= raw_len do
if value then
if i == 4 then
value = string.byte(str, i)
end
else
value = string.byte(str, i)
end
i = i + 1
end
return value
end
function encode(...)
local checksum = bit.bxor(...)
return string.char(...) .. string.char(checksum)
end
addrs = {0x01,0x03,0x05,0x07,0x09,0x0b,0x0d,0x0f,0x11,0x13,0x15,0x17,0x19,0x1b,0x1d,0x1f,0x21,0x23}
local sum = 0
for _, addr in ipairs(addrs) do
command = encode(0x04,0x04,addr,0xc8)
reply = writetoport(port, 0.1, command)
decoded = str2hex(reply)
if grp.getvalue('37/3/'.. sum)~=decoded then
grp.update('37/3/'.. sum, decoded)
end
sum = sum + 1
end
value = event.getvalue()
if value == true then
grp.update(event.dst, false)
elseif value == false then
grp.update(event.dst, true)
endAt the end, I check the state of the address where the script is and run it anew when the request is received.