/tcl-device

tcl packages for my experimental computer

Primary LanguageTcl

Device library

Now I'm using device2 instead: https://github.com/slazav/device2

This is a tcl library for making complicated experimental setups.

All operations are done using "devices". They can be physical devices connected via some interface, or high-level programs which can use other devices.

Using the library one can open a few devices, send commands and get answers (or errors if any) from them. There is also a library for writing programs which can work as "devices".

The library has a configuration file "/etc/devices.txt" which lists all avalible devices. For example, line "generator gpib -board 0 -address 6" says that communication with device "generator" is done using driver gpib with parameters -board 0 -address 6.

Then one can do something like this:

package require Device
Device generator
puts [generator cmd "*idn?"]
DeviceDelete generator

Note that library itself does not know anything about commands used by certain device, it just provides connection. For the next layer see DeviceRole library.

Library provides IO locking (one device can be used by a few programs or by severel threads in one program without collisions) and optional high-level locking (one program can lock a device for a long time).

Library provides logging of all device communications: if there is a file /var/log/tcl-device/<name> then all communication with the device is appended to this file. This allows to start/stop logging without restarting and modifing programs.

Interface (see device.tcl)

  • Device -- open a device . The command is created to access the device.
  • DeviceDelete -- close a device .
  • DeviceExists -- return true if Device is opened.
  • cmd -- Send a command and get answer
  • lock -- High-level lock. Lock lasts until the process is alive or until unlock command is run. If device is locked, other communications with this device generate an error after some timeout
  • unlock -- Unlock the device.

In case of error a tcl error is called. Use catch to process it.

Drivers (see drivers.tcl)

  • gpib_prologix -- GPIB device connected through Prologix gpib2eth converter.

    Parameters: <hostname>:<gpib address>

  • lxi_scpi_raw -- LXI device connected via ethernet (SCPI raw connection via port 5025).

    Parameters: <hostname>

  • usbtcm -- devices controlled by usbtcm driver

    Parameters: character device (such as /dev/usctcm0).

  • gpib -- Connection with linux-gpib library.

    Parameters:

    • -timeout
    • -eot
    • -secondary
    • -eos
    • -bufferlen
    • -address
    • -board
    • -trimleft
    • -trimright
    • -readymask
    • -waitready

  • spp -- Simple pipe protocol for programs.

    Parameters: program name and arguments.

  • tenma_ps -- Tenma power supply. It is a serial port connection, but with specific delays and without newline characters.

    Parameters: character device (such as /dev/ttyACM0).

  • leak_ag_vs -- Agilent VS leak detector. Use null-modem cable/adapter!

    Parameter: character device name

Simple pipe protocol (SPP)

version 001

There are two programs, "server" and "client". Client runs the server program and communicate with it using unix pipes. All data are read and written line by line in a human-readable form if possible.

When connection is opened, server writes a line with the special symbol ('#' in this example, but it can be any symbol), protocol name and version: #SPP<version>. Then it can write some text for the user which can be ignored. Then it either writes #Error: <message> and exits or writes #OK and start listening for user requests. Simbol '#' here is a special symbol which was selected in the beginning of the conversation.

Request is one line of text.

Answer of the server is a few lines of text, followed by '#Error: ' or '#OK' line. Lines of the answer text starting with the '#' symbol should be protected by doubling the symbol.

It is recommended to implement *idn? command which returns ID of the device.

version 002

If any fatal error appear server can print a line #Fatal: <message> and exit.

  • TODO: requests with several lines
  • TODO: timeouts, safe closing of the channel...
  • TODO: raw data transfer

Conversation example (see spp_server_test.tcl program):

$ ./spp_server_test.tcl
#SPP002
Welcome, dear user!
Please, type "help" if you do not know what to do.
#OK
h
#Error: Unknown command: h
help
spp_server_test -- an example of the command-line interface program.
Commands:
  write <k> <v> -- write value v into a memory slot k=0..9
  read <k>      -- read value from a memory slot k
  list -- list all commands
  help -- show this message

#OK
write 1 abc
#OK
read
#Error: wrong # args: should be "testSrv0 read k"
read 1
abc
#OK

TCL interface (see spp_client.tcl, spp_server.tcl, spp_server_async.tcl)

There is a simple tcl library to implement the protocol. To write the server create an Itcl class with all needed commands (each gets any number of argumets and returns answer or throws an error) and "list" command which returns all command names which should be available through the interface. Then run:

cl_server::run $server_class $opts

To create a connection to a server: cl_client conn $prog_name

and run commands conn cmd

See spp_server_test.tcl and spp_client_test.tcl programs.

SPP programs which can be used as devices:

All this programs supports Simple pipe protocol (SPP) and can be run from command line or through Device library.

Remote communication

You can easily add remote devices using spp interface. In the configuration file of the Device library it can be written as

lockin0          ssh <remote address> device -d lockin0
graphene_remote  ssh <remote address> graphene -i

(ssh access should be configured using keys, ssh-agent etc.)

vwait problem

There are two places in the library (locks and reading from devices) which can be done in syncroneous and asyncronious ways. For simple programs both ways are good; for tk interfaces async version is better since id does not lock the interface; in some complicated programs a nested vwait call can appear in async version causing a permanent lock.

I do not have a good solution yet, so I just have both versions which can be swiched by Device::sync variable (default 0).