How To: Connect a digitizer to a UNIX platform for use with ARC/INFO
How to connect a digitizer for proper use with ARC/INFO.
The following steps apply to all digitizers and all UNIX platforms:
1. Set up communication parameters.
The digitizer and computer ports must be set up with identical communication parameters. These are the recommended settings:
Baud Rate: 9600
Data Bits: 8
Stop Bits: 1
Parity: No Parity (Disabled)
Data Format: ASCII
Resolution: 1000 lpi (lines per inch)
Report Mode: Point
Local echo: off
Line feed: off
Most digitizers require parameters be set with dip switches or menu soft switches. Refer to your digitizer user manual or the ARC/INFO Device Interface Guide for more specific information.
This is the most important part of digitizer installation regardless of whether the device is supported or not. If your digitizer and your computer can not communicate, ARC/INFO will not recognize what the digitizer is sending.
2. Configure the host machine.
A. Set the permissions on the host port to be rw (read, write) for all. To check the current permissions use the following command:
ls -l /dev/ttya (or whatever tty device you are using)
The above command will return something like this:
lrw-rw-rw- 1 root root 6 Jul 21 11:27 /dev/ttya
If the permissions do not look like this, switch users to root and issue the following to change them:
chmod 666 /dev/ttya
B. Check that the 'login' is disabled for the host port.
- Go into the ADMINTOOL
- Press the 'Serial Port Manager'
- Highlight the desired Port (a or b)
- Press the 'EDIT' button
- Make sure the Service is DISABLED, if not click 'DISABLED' and then 'APPLY'
- Use SMIT (administrator)
- Select devices -> tty -> change/show char. of tty
- Click on the tty you are using and among the stats shown is the 'enable login' field.
-This should say 'disabled'. If not, click on that field and click on the 'up' arrow.
These instructions may be slightly different depending on your version of AIX.
Generic BSD UNIX:
- Modify the /etc/inittab file so that the entry for getty on the serial port is set to "off" and not respawn. For init to re-read the inittab file run:
# kill -1 1
4. Use the Arc DIGTEST command to test the communications and parameters:
Arc: DIGTEST <format file> /dev/tty00:9600:8bit:none
If DIGTEST does not initialize correctly, then communications have not been established. Check the settings again. If they are correct, then check the cable, and if available, use an in-line tester. If everything is functional, it may be that your digitizer requires a null-modem to properly establish the RS-232C protocol.
If your UNIX system is not listed above, or if you need more detailed information, refer to your operating system documentation.