- From: Jiri Baum <jiri_at_baum.com.au>
- Date: Thu, 17 Jul 2003 02:36:56 +1000
Hello,
I need to parse user-supplied strings to comedi addresses (to connect
comedi and MatPLC), but there doesn't appear to be a standard function
for that, or even a convention about how the addresses should look.
Would the following format make sense?
Each address would have the form (some parts optional):
device: type subdevice.channel options
Examples:
I2.3 - digital input, device 0, subdevice 2, channel 3.
1:X7.3/2_DIFF - converted analog input, device 1, subdevice 7, channel
3, range 2, reference AREF_DIFF.
U.2 - analog output, device 0, subdevice 0, channel 2, default range
and reference.
Details:
device is either the device filename, or the number of the device
("/dev/comedi" will be prepended in the latter case). The device
specification may be omitted, including the colon, in which case 0
will be used.
type denotes the direction, kind and conversion to physical units; it
is mandatory
- I - digital input
- O or Q - digital output
- N - analog input (raw) (mnemonic: iN)
- U - analog output (raw) (mnemonic: oUt)
- X - analog input converted to physical units
- Y - analog output converted from physical units
(BTW, anyone have any better / more logical ideas for these letters?)
subdevice.channel are obvious; one or the other may be omitted, but
not both; omitted parts default to 0.
1 = 1.0
.1 = 0.1
There are two options, either or both of which may be used for analog
inputs and outputs; there are no options for digital I/O.
/range - specifies the range to be used, as a number. Default 0.
_ref - specifies the reference to be used, either as a number, or as
a keyword (so 0, GROUND and GND are all equivalent). Default GROUND.
Mnemonic: the value at the low end; hence underscore.
Any comments, please?
Jiri
--
Jiri Baum <jiri_at_baum.com.au> http://www.csse.monash.edu.au/~jirib
MAT LinuxPLC project --- http://mat.sf.net --- Machine Automation Tools
Received on 2003-07-16Z15:36:56