The script halshow can help you find your away around a running HAL. This is a very specialized system and it must connect to a working HAL. It can not run stand alone because it relies on the ability of HAL to report what it knows of itself through the halcmd interface library. It is discovery based. Each time halshow runs with a different EMC configuration it will be different.
As we will soon see, this ability of HAL to document itself is one key to making an effective CNC system.
At the left of its display as shown in figure is a tree view, somewhat like you might see with some file browsers. At the right is a tabbed notebook with tabs for show and watch.
The tree shows all of the major parts of a HAL. In front of each is a small plus (+) or minus (-) sign in a box. Clicking the plus will expand that tree node to display what is under it. If that box shows a minus sign clicking it will close that section of the tree.
You can also expand or collapse the tree display using the Tree View menu at the upper left edge of the display. This menu is shown in figure xx
Clicking on the node name rather than its plus or minus sign, the word ``Components'' for example, will show you all that hal knows about the contents of it. Figure shows a list exactly like you will see if you click the ``Components'' name while you are running a standard m5i20 servo card. The information display is exactly like those shown in traditional text based HAL analysis tools. The advantage here is that we have mouse click access. Access that can be as broad or as focused as you need.
If we take a closer look at the tree display we can see that the six major parts of a HAL can all be expanded at least one level. As these levels are expanded you can get more focused with the reply when you click on the rightmost tree node. You will find that there are some hal pins and parameters that show more than one reply. This is do to the nature of the search routines in halcmd itself. If you search one pin you may get two like this.
Owner Type Dir Value Name
06 bit -W TRUE parport.0.pin-10-in
06 bit -W FALSE parport.0.pin-10-in-not
Below the show area on the right is a set of widgets that will allow you to play with the running HAL. The commands you enter here and the effect that they have on the running HAL are not saved. They will persist as long as the emc remains up but are gone as soon as it is.
The entry box labeled Test Hal Command : will accept any of the commands listed for halcmd. These include;
Let's use this editor to add a differential module to a hal and connect it to axis position so that we could see the rate of change in position, ie acceleration. We first need to load a hal module named blocks, add it to the servo thread, then connect it to the position pin of an axis. Once that is done we can find the output of the differentiator in halscope. So let's go. (yes I looked this one up.)
ID Type Name
10 User halcmd29800
09 User halcmd29374
08 RT blocks
06 RT hal_parport
05 RT scope_rt
04 RT stepgen
03 RT motmod
02 User iocontrol
Owner CodeAddr Arg FP Users Name
08 E0B97630 E0DC7674 YES 0 ddt.0
03 E0DEF83C 00000000 YES 1 motion-command-handler
03 E0DF0BF3 00000000 YES 1 motion-controller
06 E0B541FE E0DC75B8 NO 1 parport.0.read
06 E0B54270 E0DC75B8 NO 1 parport.0.write
06 E0B54309 E0DC75B8 NO 0 parport.read-all
06 E0B5433A E0DC75B8 NO 0 parport.write-all
05 E0AD712D 00000000 NO 0 scope.sample
04 E0B618C1 E0DC7448 YES 1 stepgen.capture-position
04 E0B612F5 E0DC7448 NO 1 stepgen.make-pulses
04 E0B614AD E0DC7448 YES 1 stepgen.update-freq
addf <functname> <threadname> [<position>]We already know the functname=ddt.0 so let's get the thread name right by expanding the thread node in the tree. Here we see two threads servo-thread and base-thread. The position of ddt.0 in the thread is not critical.
Next we need to connect this block to something. But how do we know what pins are available. The answer is look under pins. There we find ddt and see this.
Owner Type Dir Value Name
08 float R- 0.00000e+00 ddt.0.in
08 float -W 0.00000e+00 ddt.0.out
Owner Type Dir Value Name
03 float -W 0.00000e+00 axis.0.motor-pos-cmd ==> Xpos-cmd
Type Value Name
float 0.00000e+00 Xpos-cmd
The Hal Show Area uses halcmd to discover what is happening in a running HAL. It gives you complete information about what it has discovered. It also updates as you issue commands from the little editor panel to modify that HAL. There are times when you want a different set of things displayed without all of the information available in this area. That is where the Hal Watch Area is of value.
Clicking the watch tab produces a blank canvas. You can add signals and pins to this canvas and watch their values.0.1 You can add signals or pins when the watch tab is displayed by clicking on the name of it. Figure shows this canvas with several ``bit'' type signals. These signals include enable-out for the first three axes and two of the three iocontrol ``estop'' signals. Notice that the axes are not enabled even though the estop signals say that the EMC is not in estop. A quick look at themc shows that the condition of the EMC is ESTOP RESET. The amp enables do not turn true until the machine has been turned on.
The two colors of circles, aka leds, always show dark brown when a bit signal or pin is false. They show the light yellow whenever that signal is true. If you select a pin or signal that is not a bit typed signal, watch will show the numerical value.
Watch will quickly allow you to test switches or see the effect of
changes that you make to EMC while using the graphical interface.
Watch's refresh rate is a bit slow to see stepper pulses but you can
use it for these if you move an axis very slowly or in very small
increments of distance. If you've used IO_Show in EMC, the watch
page in halshow can be setup to watch a parport much as it did.