Hello, I have this code but I got this error , can anyOne help me with this please ?
I have and 0x80 in the address but says that cannot be cast to class
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I don’t think you are calling writeBytes correctly, and i don’t think you are giving it a java.lang.byte.
https://docs.inductiveautomation.com/display/DOC81/system.serial.writeBytes
Something is coercing [adress] into a Python ‘singleton’, which likely means True, False or None, but I’m not sure why…
y = 0
portNum = "COM10"
address = 0x80
cmd = 0x04
qty = 0x01
confirm = 0x0B
chkSum3 = adress ^ cmd ^ qty
chkSum2 = adress ^ confirm
chkConfNoError = adress ^ 3 ^ 0 ^ qty
with system.serial.port(
port = portNum,
bitRate =system.serial.BIT_RATE_19200,
dataBits = system.serial.DATA_BITS_8,
handshake = system.serial.HANDSHAKE_NONE,
hardwareFlowControl = False,
parity = system.serial.PARITY_MARK,
stopBits = system.serial.STOP_BITS_1) as port:
port.writeBytes([adress])
with system.serial.port(
port = portNum,
bitRate =system.serial.BIT_RATE_19200,
dataBits = system.serial.DATA_BITS_8,
handshake = system.serial.HANDSHAKE_NONE,
hardwareFlowControl = False,
parity = system.serial.PARITY_SPACE,
stopBits = system.serial.STOP_BITS_1) as port2:
port2.writeBytes([cmd, qty, chkSum3])
#time.sleep(0.001)
#port2.writeBytes([qty])
#time.sleep(0.001)
#port2.writeBytes([chkSum3])
response = port2.readBytes(5, 5)
#time.sleep(0.015)
with system.serial.port(
port = portNum,
bitRate =system.serial.BIT_RATE_19200,
dataBits = system.serial.DATA_BITS_8,
handshake = system.serial.HANDSHAKE_NONE,
hardwareFlowControl = False,
parity = system.serial.PARITY_MARK,
stopBits = system.serial.STOP_BITS_1) as port:
port.writeBytes([adress])
with system.serial.port(
port = portNum,
bitRate =system.serial.BIT_RATE_19200,
dataBits = system.serial.DATA_BITS_8,
handshake = system.serial.HANDSHAKE_NONE,
hardwareFlowControl = False,
parity = system.serial.PARITY_SPACE,
stopBits = system.serial.STOP_BITS_1) as port2:
while True:
port2.writeBytes([confirm, chkSum2])
#time.sleep(0.001)
#port2.writeBytes([chkSum2])
res = list(port2.readBytes(5, 5))
#time.sleep(0.015)
y = y + 1
if res == [adress, 3, 0, qty, chkConfNoError]:
break
print "Dirección " + str(adress)
print res
print list(response)
print str(y)
The point of the system.serial.port context manager is that you don’t have to open and close the port manually - you just write all your code that has to interact with the port within the indented scope.
Try this, and see what the output is of the two print statements before the first write:
y = 0
portNum = "COM10"
adress = 0x80
cmd = 0x04
qty = 0x01
confirm = 0x0B
chkSum3 = adress ^ cmd ^ qty
chkSum2 = adress ^ confirm
chkConfNoError = adress ^ 3 ^ 0 ^ qty
with system.serial.port(
port = portNum,
bitRate =system.serial.BIT_RATE_19200,
dataBits = system.serial.DATA_BITS_8,
handshake = system.serial.HANDSHAKE_NONE,
hardwareFlowControl = False,
parity = system.serial.PARITY_MARK,
stopBits = system.serial.STOP_BITS_1) as port:
toWrite = [adress]
print toWrite
print type(toWrite)
port.writeBytes(toWrite)
port.writeBytes([cmd, qty, chkSum3])
#time.sleep(0.001)
#port.writeBytes([qty])
#time.sleep(0.001)
#port.writeBytes([chkSum3])
response = port.readBytes(5, 5)
#time.sleep(0.015)
port.writeBytes([adress])
while True:
port.writeBytes([confirm, chkSum2])
#time.sleep(0.001)
#port.writeBytes([chkSum2])
res = list(port.readBytes(5, 5))
#time.sleep(0.015)
y = y + 1
if res == [adress, 3, 0, qty, chkConfNoError]:
break
print "Dirección " + str(adress)
print res
print list(response)
print str(y)
I’m trying to understand your code (@PGriffith’s code). Is it possible that port2 isn’t declared? If it is declared somewhere under the hood, where?
The error is right here :
port.writeBytes([address])
That was just a typo from rewriting the original code.
Yeah, I want to see the output from the print statements in my modified code:
toWrite = [adress]
print toWrite
print type(toWrite)
port.writeBytes(toWrite)
Yes , I got a type = list and towrite I got [128] , but If I put 127 everything is fine
y = 0
portNum = “COM10”
address = 0x80
cmd = 0x04
qty = 0x01
confirm = 0x0B
chkSum3 = adress ^ cmd ^ qty
chkSum2 = adress ^ confirm
chkConfNoError = adress ^ 3 ^ 0 ^ qty
with system.serial.port(
port = portNum,
bitRate =system.serial.BIT_RATE_19200,
dataBits = system.serial.DATA_BITS_8,
handshake = system.serial.HANDSHAKE_NONE,
hardwareFlowControl = False,
parity = system.serial.PARITY_MARK,
stopBits = system.serial.STOP_BITS_1) as port:
port.writeBytes([adress])You might need to work around a Jython bug:
It isn’t really a jython bug. Just that java bytes are signed, so java byte arrays must be made of values from -128 to 127.
I get it , but I need to send 128, do you know if is there more options?
How to send a number without the operator - 128
The simplest expression to get the proper signed byte is ((b + 128) & 0xff) - 128. For each byte.
Seems like we should make these functions easier to call… perhaps by accepting int[] as well.
3 Likes
I understand but we need with no sign
You actually do, because that is how the underlying Java works. You can use the expression @pturmel mentioned in a helper function to format the bytes as they make sense to you to what is required for the array. Combining with what @PGriffith mentioned earlier should yield something like:
y = 0
portNum = "COM10"
adress = 0x80
cmd = 0x04
qty = 0x01
confirm = 0x0B
chkSum3 = adress ^ cmd ^ qty
chkSum2 = adress ^ confirm
chkConfNoError = adress ^ 3 ^ 0 ^ qty
def toSignedBytes(bytesIn):
''' Convert a list of unsigned byte values to signed values.
If a single integer value is given, a list is still returned
'''
if isinstance(bytesIn, int):
bytesIn = [bytesIn]
return [((byte+128) & 255)-128 for byte in bytesIn]
# Initialize the byte lists
cmdList = toSignedBytes([address, cmd, qty, chkSum3])
confirmList = toSignedBytes([address, confirm, chkSum2])
with system.serial.port(
port = portNum,
bitRate =system.serial.BIT_RATE_19200,
dataBits = system.serial.DATA_BITS_8,
handshake = system.serial.HANDSHAKE_NONE,
hardwareFlowControl = False,
parity = system.serial.PARITY_MARK,
stopBits = system.serial.STOP_BITS_1) as port:
# Send the command
print "Dirección: ", str(adress)
print "Cmd bytes:", cmdList
port.writeBytes(cmdList)
# Get the response
cmdResponse = list(port.readBytes(5, 5))
print "Cmd response: ", (cmdResponse)
print "Confirm bytes: ", confirmList
while True:
# Send the confirm
port.writeBytes(confirmList)
# Get the response
confirmResponse = list(port.readBytes(5, 5))
y = + 1
if res == [adress, 3, 0, qty, chkConfNoError]:
break
print "Confirm Response: ", confirmResponse
print "Tries: ", str(y)
2 Likes
Yes but I am looking for the opposite , I mean upside down
Opening and closing ports is not needed. Should we also avoid delays between calls?
I have a while looking up for posts using the Serial Module with delays in between
As a general practice, a lockable external resource like a serial port should only be held by your application while it’s actively being read to or written from. There are exceptions, but I would stick to that as a guideline before doing something else.