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Re: Serial Port Problems

Dear Ethan,

Your scale has a DB9, DB25 or USB connector?
It is important to make sure that the cable you are using has the correct pinout.
Your scale has come with a cable from manufacturer or you set up the communication cable yourself?
The DB9 serial cable for communication use, in general, only 3 pins, Tx, Rx and Gnd. If your instrument follows the standard RS232.
Then you need to know what are the serial communication parameters that the scale are using (data bits, parity, stop bit, bps) to be able to configure your acquisition program correctly.
Some instruments send information over the serial port automatically as soon as they are turned on, others send after setting the instrument by typing some commands at the keyboard, and there are some instruments which send information only after receiving commands by the computer. 

The manufacturer's manual should provide this information.
And finally use an acquisition program to verify that data is being received correctly to be processed. 

I have some information about serial communication on these sites:

http://www.c2o.pro.br/automacao/x834.html
http://www.c2o.pro.br/automacao/x2467.html

Are in Portuguese. Use Google translator.

Any question, email-me,
Markos



On 03-10-2014 09:43, Ethan Rosenberg wrote:

Dear List -

I am trying to capture data from a serial port and write it to a file.

ethan@meow:/var/www$ cat /dev/ttyS0 > scale_value.html
cat: /dev/ttyS0: Device or resource busy

root@meow:/var/www#  cat /proc/tty/driver/serial
serinfo:1.0 driver revision:

0: uart:16550A port:000003F8 irq:4 tx:90 rx:270 brk:2 RTS|CTS|DTR|DSR|CD
1: uart:16550A port:00001C90 irq:17 tx:19 rx:0 CTS|DSR|CD
2: uart:unknown port:000003E8 irq:4
3: uart:unknown port:000002E8 irq:3

root@meow:/var/www# cat /proc/interrupts
           CPU0       CPU1
  0:         42          0   IO-APIC-edge      timer
  1:          3          0   IO-APIC-edge      i8042
  4:         74         89   IO-APIC-edge      serial
  6:          2          1   IO-APIC-edge      floppy
  8:          0          1   IO-APIC-edge      rtc0
  9:          1          2   IO-APIC-fasteoi   acpi
 12:          5          0   IO-APIC-edge      i8042
16: 148679 155632 IO-APIC-fasteoi uhci_hcd:usb1, uhci_hcd:usb4, ehci_hcd:usb7 17: 9 8 IO-APIC-fasteoi uhci_hcd:usb2, uhci_hcd:usb5, i801_smbus 18: 131 143 IO-APIC-fasteoi uhci_hcd:usb3, ehci_hcd:usb6, uhci_hcd:usb8 
 40:   54993721          0  HPET_MSI-edge      hpet2
 41:          0   53507648  HPET_MSI-edge      hpet3
 42:    1041026     920449   PCI-MSI-edge      eth0
 43:     524549     476624   PCI-MSI-edge      ahci
 44:         11          9   PCI-MSI-edge      mei_me
 45:      46800      46570   PCI-MSI-edge      i915
 46:       1488       1583   PCI-MSI-edge      snd_hda_intel
NMI:      37245      37177   Non-maskable interrupts
LOC:         16         12   Local timer interrupts
SPU:          0          0   Spurious interrupts
PMI:      37245      37177   Performance monitoring interrupts
IWI:     258822     264271   IRQ work interrupts
RTR:          0          0   APIC ICR read retries
RES:    5271209    5278411   Rescheduling interrupts
CAL:        433        693   Function call interrupts
TLB:    2917013    2903216   TLB shootdowns
TRM:          0          0   Thermal event interrupts
THR:          0          0   Threshold APIC interrupts
MCE:          0          0   Machine check exceptions
MCP:       1061       1061   Machine check polls
ERR:          0
MIS:          0

/dev/ttyS1, Line 1, UART: 16550A, Port: 0x1c90, IRQ: 17
    Baud_base: 115200, close_delay: 50, divisor: 0
    closing_wait: none
    Flags: spd_normal skip_test

root@meow:/var/www#  setserial /dev/ttyS0 -a
/dev/ttyS0, Line 0, UART: 16550A, Port: 0x03f8, IRQ: 4
    Baud_base: 115200, close_delay: 50, divisor: 0
    closing_wait: 3000
    Flags: spd_normal skip_test

How do I get rid of the busy message?

TIA

Ethan
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