pyserial to read from DS1615 temperature recorder chip
Hi there, I am trying to use pyserial to read data from a temperature logger device (T-logger). T-logger is based on the DS1615 temperature recorder chip (Dallas Semiconductor). According to the DS1615 docs, writing to the chip is performed one byte at a time. To read from the chip, one must issue the read page command (33h), followed by the two-byte address of the requested page (pages are 32 bytes long). After receiving this, the DS1615 will send the data in a burst of (up to) 32 bytes. I can send data to the device, e.g. I can make the device's LED blink with the test command (44h), but I am unable to read from it. Connection parameters below are according to DS1615 docs. import serial s = serial.Serial(0, baudrate=9600, bytesize=8, parity='N', stopbits=1, timeout=None) s.write(\x33) s.write(\x00) s.write(\x00) s.read() # \x00 is returned here. This byte was already in the receive buffer before issueing the write commands. s.read() # The interpreter is blocked here as there is nothing to read from the serial port. I'm completely clueless and would really appreciate your comments. If it helps, I can post a log from a serial port monitor captured when the provided T-logger program pulls data from the device, as well as a log when pyserial is used. And finally, this is a snippet of some basic code found on the web, that is suppose to do what I want (untested by me): open COM1:9600,N,8,1,CS0,DS0,CD0,ME,FE as 1 print #1, chr$(H33);chr$(H00);chr$(H00) result$ = input$(34, #1) Many thanks, alex -- http://mail.python.org/mailman/listinfo/python-list
Re: pyserial to read from DS1615 temperature recorder chip
On 2006-07-24 14:03:30, [EMAIL PROTECTED] wrote: To read from the chip, one must issue the read page command (33h), followed by the two-byte address of the requested page (pages are 32 bytes long). After receiving this, the DS1615 will send the data in a burst of (up to) 32 bytes. I'm not sure what you mean when you say it will send up to 32 bytes. If you mean that it sends bytes until all existing values have been sent -- did you make sure you have any values in the buffer? (Just asking the obvious... :) Gerhard -- http://mail.python.org/mailman/listinfo/python-list
Re: pyserial to read from DS1615 temperature recorder chip
On 2006-07-24, Gerhard Fiedler [EMAIL PROTECTED] wrote: On 2006-07-24 14:03:30, [EMAIL PROTECTED] wrote: To read from the chip, one must issue the read page command (33h), followed by the two-byte address of the requested page (pages are 32 bytes long). After receiving this, the DS1615 will send the data in a burst of (up to) 32 bytes. I'm not sure what you mean when you say it will send up to 32 bytes. Registers are in 32-byte pages. If you request register N, the device sends register N followed by the remainder of the 32-byte page that contains address N. If you request the first register on a page, you'll get 32 bytes back. If you request the last register on a page, you'll get one 1 back. -- Grant Edwards grante Yow! If I pull this SWITCH at I'll be RITA HAYWORTH!! Or visi.coma SCIENTOLOGIST! -- http://mail.python.org/mailman/listinfo/python-list
Re: pyserial to read from DS1615 temperature recorder chip
On 2006-07-24, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote: import serial s = serial.Serial(0, baudrate=9600, bytesize=8, parity='N', stopbits=1, timeout=None) s.write(\x33) s.write(\x00) s.write(\x00) s.read() # \x00 is returned here. This byte was already in the receive buffer before issueing the write commands. s.read() # The interpreter is blocked here as there is nothing to read from the serial port. Can you verify that the device is actually responding by watching the data line with an oscilloscope? I'm completely clueless and would really appreciate your comments. If it helps, I can post a log from a serial port monitor captured when the provided T-logger program pulls data from the device, I take it that means that other programs are able to read from the device? as well as a log when pyserial is used. Logs of the serial traffic would be helpful. -- Grant Edwards grante Yow! It's the land of at DONNY AND MARIE as promised visi.comin TV GUIDE! -- http://mail.python.org/mailman/listinfo/python-list
Re: pyserial to read from DS1615 temperature recorder chip
Gerhard Fiedler wrote: On 2006-07-24 14:03:30, [EMAIL PROTECTED] wrote: To read from the chip, one must issue the read page command (33h), followed by the two-byte address of the requested page (pages are 32 bytes long). After receiving this, the DS1615 will send the data in a burst of (up to) 32 bytes. I'm not sure what you mean when you say it will send up to 32 bytes. If you mean that it sends bytes until all existing values have been sent -- did you make sure you have any values in the buffer? (Just asking the obvious... :) Gerhard Thanks Gerhard, Up to 32 bytes means that the chip sends the bytes from the address you give up to the end of the memory page that contains this address. Thus if you give the address of the beginning of a memory page (e.g. like here H for the beginning of the first page, which contains control registers and the current temperature register), you get 32 bytes. alex -- http://mail.python.org/mailman/listinfo/python-list
Re: pyserial to read from DS1615 temperature recorder chip
Thanks Grant, Can you verify that the device is actually responding by watching the data line with an oscilloscope? I don't have an oscilloscope but the device does respond (LED blinks) when I send it a test command (44H). I take it that means that other programs are able to read from the device? Yes, the device comes with a little GUI program to read the logged temperatures, calibrate, etc... Works fine, but I would like to read distributed loggers over the network with python and sockets. Logs of the serial traffic would be helpful. Here they are. First a log of the traffic generated by the T-logger GUI program, abtained with Portmon. ### TRAFFIC WHEN THE PROGRAM IS LAUNCHED: 0 0. TLogger.exe IRP_MJ_CREATE Serial0 Options: Open 0 0.6174 SUCCESS 1 0. TLogger.exe IOCTL_SERIAL_SET_WAIT_MASK Serial0 Mask: RXCHAR TXEMPTY CTS DSR RLSD BRK ERR RING 1 0.0726 SUCCESS 2 0. TLogger.exe IOCTL_SERIAL_PURGE Serial0 Purge: TXABORT RXABORT TXCLEAR RXCLEAR 2 0.0698 SUCCESS 3 0. TLogger.exe IOCTL_SERIAL_SET_TIMEOUTS Serial0 RI:-1 RM:0 RC:0 WM:0 WC:5000 3 0.0168 SUCCESS 4 0. TLogger.exe IOCTL_SERIAL_GET_BAUD_RATE Serial0 4 0.0279 SUCCESS 5 0. TLogger.exe IOCTL_SERIAL_GET_LINE_CONTROL Serial0 5 0.0196 SUCCESS 6 0. TLogger.exe IOCTL_SERIAL_GET_CHARS Serial0 6 0.0223 SUCCESS 7 0. TLogger.exe IOCTL_SERIAL_GET_HANDFLOW Serial0 7 0.0196 SUCCESS 8 0. TLogger.exe IOCTL_SERIAL_GET_BAUD_RATE Serial0 8 0.0196 SUCCESS 9 0. TLogger.exe IOCTL_SERIAL_GET_LINE_CONTROL Serial0 9 0.0168 SUCCESS 10 0. TLogger.exe IOCTL_SERIAL_GET_CHARS Serial0 10 0.0168 SUCCESS 11 0. TLogger.exe IOCTL_SERIAL_GET_HANDFLOW Serial0 11 0.0168 SUCCESS 12 0. TLogger.exe IOCTL_SERIAL_SET_BAUD_RATE Serial0 Rate: 9600 12 0.1285 SUCCESS 13 0. TLogger.exe IOCTL_SERIAL_CLR_RTS Serial0 13 0.0782 SUCCESS 14 0. TLogger.exe IOCTL_SERIAL_SET_DTR Serial0 14 0.0810 SUCCESS 15 0. TLogger.exe IOCTL_SERIAL_SET_LINE_CONTROL Serial0 StopBits: ERROR Parity: NONE WordLength: 8 15 0.0698 SUCCESS 16 0. TLogger.exe IOCTL_SERIAL_SET_CHAR Serial0 EOF:1a ERR:0 BRK:0 EVT:0 XON:11 XOFF:13 16 0.0531 SUCCESS 17 0. TLogger.exe IOCTL_SERIAL_SET_HANDFLOW Serial0 Shake:1 Replace:0 XonLimit:8 XoffLimit:8 17 0.0754 SUCCESS 18 0. TLogger.exe IOCTL_SERIAL_SET_WAIT_MASK Serial0 Mask: RXCHAR TXEMPTY CTS DSR RLSD BRK ERR RING 18 0.1145 SUCCESS 19 0. TLogger.exe IOCTL_SERIAL_SET_WAIT_MASK Serial0 Mask: RXCHAR TXEMPTY CTS DSR RLSD BRK ERR RING 19 0.0531 SUCCESS 20 0. TLogger.exe IOCTL_SERIAL_WAIT_ON_MASK Serial0 ### TRAFFIC WHEN THE PROGRAM READS CURRENT TEMP FROM DEVICE: 21 0. TLogger.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 21 0.1034 SUCCESS 22 0. TLogger.exe IRP_MJ_WRITE Serial0 Length 1: 33 22 0.3269 SUCCESS 20 9.28649032 SUCCESS 23 0. TLogger.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 23 0.0587 SUCCESS 24 0. TLogger.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 24 0.0559 SUCCESS 25 0. TLogger.exe IOCTL_SERIAL_GET_PROPERTIES Serial0 25 0.0168 SUCCESS 26 0. TLogger.exe IRP_MJ_WRITE Serial0 Length 1: 00 27 0. TLogger.exe IOCTL_SERIAL_SET_WAIT_MASK Serial0 Mask: RXCHAR TXEMPTY CTS DSR RLSD BRK ERR RING 27 0.0726 SUCCESS 28 0. TLogger.exe IOCTL_SERIAL_WAIT_ON_MASK Serial0 26 0.00107611 SUCCESS 28 0.00097666 SUCCESS 29 0. TLogger.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 29 0.0587 SUCCESS 30 0. TLogger.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 30 0.0503 SUCCESS 31 0. TLogger.exe IOCTL_SERIAL_GET_PROPERTIES Serial0 31 0.0196 SUCCESS 32 0. TLogger.exe IRP_MJ_WRITE Serial0 Length 1: 00 33 0. TLogger.exe IOCTL_SERIAL_SET_WAIT_MASK Serial0 Mask: RXCHAR TXEMPTY CTS DSR RLSD BRK ERR RING 33 0.0531 SUCCESS 34 0. TLogger.exe IOCTL_SERIAL_WAIT_ON_MASK Serial0 32 0.00102583 SUCCESS 34 0.00098811 SUCCESS 35 0. TLogger.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 35 0.0559 SUCCESS 36 0. TLogger.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 36 0.0726 SUCCESS 37 0. TLogger.exe IOCTL_SERIAL_GET_COMMSTATUS Serial0 37 0.0559 SUCCESS 38 0. TLogger.exe IOCTL_SERIAL_SET_WAIT_MASK Serial0 Mask: RXCHAR TXEMPTY CTS DSR RLSD BRK ERR RING 38 0.1173 SUCCESS 39 0. TLogger.exe IOCTL_SERIAL_WAIT_ON_MASK Serial0 39 0.00934281 SUCCESS 40 0. TLogger.exe IOCTL_SERIAL_SET_WAIT_MASK Serial0 Mask: RXCHAR TXEMPTY CTS DSR RLSD BRK ERR RING 40 0.0922 SUCCESS 41 0. TLogger.exe IOCTL_SERIAL_WAIT_ON_MASK Serial0 41 0.1034
Re: pyserial to read from DS1615 temperature recorder chip
On 2006-07-24, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote: Logs of the serial traffic would be helpful. Here they are. First a log of the traffic generated by the T-logger GUI program, abtained with Portmon. I try to avoid Windows as much as humanly possible, but one thing that appears to be different is that Tlogger clears RTS and your program sets it. Try clearing RTS in your program when you set up the serial port. If clearing RTS doesn't help, I guess I'd try different flow control settings (try enabling and disabling RTS/CTS flow control). Since you're dealing with binary data, make sure that Xon/Xoff flow control is disabled. -- Grant Edwards grante Yow! What's the MATTER at Sid?... Is your BEVERAGE visi.comunsatisfactory? -- http://mail.python.org/mailman/listinfo/python-list
Re: pyserial to read from DS1615 temperature recorder chip
Grant Edwards wrote: On 2006-07-24, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote: Logs of the serial traffic would be helpful. Here they are. First a log of the traffic generated by the T-logger GUI program, abtained with Portmon. I try to avoid Windows as much as humanly possible, but one thing that appears to be different is that Tlogger clears RTS and your program sets it. Try clearing RTS in your program when you set up the serial port. If clearing RTS doesn't help, I guess I'd try different flow control settings (try enabling and disabling RTS/CTS flow control). Since you're dealing with binary data, make sure that Xon/Xoff flow control is disabled. It could also be a timing issue or handshaking problem. Having to write to the chip a byte at a time implies that it could take it a little while to digest each byte; longer than the natural character time for the baud rate, that is. I'm not sure if I'm reading the portmon output correctly, but it looks like the T-logger program is waiting for CTS (or possibly some other condition) before sending each byte. The Python program does not appear to be doing so, it's just sending the three bytes, bang bang bang. -- JK -- http://mail.python.org/mailman/listinfo/python-list
