Part C: Managing Change Groups
| Site: | QSC |
| Course: | Q-SYS QuickStarts |
| Book: | Part C: Managing Change Groups |
| Printed by: | Guest user |
| Date: | Sunday, 28 April 2024, 6:38 PM |
Description
Lesson Description
Poll multiple controls at once using change groups and schedule change groups to automatically report their statusVideo Transcript
0:08
Welcome back. We’ve gone over a variety of commands to change our controls via external devices,
0:14
and one of the most common commands is to poll a control’s status.
0:18
If you frequently need to poll a lot of controls,
0:20
you’ll be interested in using Change Groups and Change Group Scheduling.
0:25
One of the most frequent tech support questions we get is about how to use these features
0:29
and its one of the main reasons we decided to make this video.
0:32
Once we’ve taken you through this, creating Change Groups and Scheduling them will be perfectly clear.
0:37
To keep this example as simple as possible,
0:40
we’ll continue with our current design in Emulation Mode and issue commands using our Telnet session.
0:45
First we need to create a Change Group, which will let us efficiently poll the values of both
0:50
the Gain and Mute controls. We’ll use the “cgc 1” command, or “Change Group Create.”
0:57
We’re labeling this Change Group as the number 1
1:00
you could use any positive number of virtually any length,
1:03
but only four change groups can be created per remote session so the number 1 will work fine.
1:09
When you hit enter, the Change Group is created, even though you won’t receive a response.
1:13
Next let’s add some controls into this Change Group. We’ll use the “cga” command, or “Change Group Add”.
1:21
Type “cga 1 GainGain” and press Enter, and “cga 1 GainMute” and press Enter.
1:30
Once again, there is no response to these commands,
1:32
but you have successfully added controls to your Change Group.
1:36
Now we can poll the change group to find out what all of its controls are currently set to.
1:40
Type ‘cgp 1’ (or Change Group Poll 1) and press Enter.
1:47
You will get a list of the Control Value responses for all controls within the group.
1:51
This is what always happens the first time you issue a Change Group Poll on a change group.
1:56
You will also see ‘cgpa’, which means Change Group Poll Acknowledge.
2:02
Depending on how you’re using the data from this poll,
2:04
parsing these acknowledgements may be burdensome,
2:07
so there’s an alternative called “cgpna” or “Control Group Poll No Ack”.
2:14
This gives you the same Control Values, but doesn’t include the ‘cgpa’ acknowledgement.
2:19
But wait - not only did we not get that cgpa, we didn’t get any control values at all. Why?
2:26
Well this is a good time to explain how Change Groups work internally.
2:31
When you add controls to a Change Group, they are marked internally as ‘Dirty Controls’
2:36
meaning that they have not yet reported their current status.
2:39
Once a polling response occurs, every control is marked as a ‘Clean Control’
2:43
and won’t report its value again when the next poll is requested.
2:47
Only if someone changes the control, within Q-Sys or via an external control method,
2:52
will the control be considered ‘dirty’ again.
2:55
Let’s go back to Designer and move the knob to a different setting.
2:58
Now go back to the Telnet session and type ‘cgpna 1’ and Enter.
3:05
We see the Control Value for the Gain control but not the Mute button.
3:09
This is because the Gain became ‘dirty’ when we changed it, yet the Mute button is still ‘clean.’
3:14
And now that the Gain control value has been reported, it’s clean again too.
3:18
So, Change Groups make it easy to poll a few, dozens or hundreds of controls with a single command.
3:24
But, what if you need to have Q-Sys automatically send updates out without being sent poll commands?
3:31
That is the purpose of Change Group Schedules.
3:33
A Change Group Schedule is basically a timer that tells Q-Sys to automatically issue a
3:38
Change Group Poll command to itself and return to results to you.
3:42
This command is called ‘cgs’ or Change Group Schedule,
3:47
but this command also adds that Poll Acknowledge response each time the timer expires.
3:51
You don’t want to receive a “cgpa” report every 100 ms,
3:55
so we recommend using the Change Group Schedule No Ack command instead, or ‘cgsna.’
4:03
We’re going to poll Change Group 1, and we just need to tell Q-Sys how often we want to
4:07
receive an update on this group. We’ll enter 100 for 100ms.
4:12
This can be set as low a 30ms or as high as you want. A value of 5000 would represent 5 seconds.
4:19
As the programmer of the control system, only you will know what to make this value.
4:24
Your control system processor might be a little slow and you need updates to come less frequently.
4:29
Or your system could be perfectly capable of receiving anything Q-Sys can throw at it
4:34
and you choose the minimum of 30ms. It’s up to you and you can change the polling interval at any time,
4:40
even after the schedule is already running.
4:42
Alright, let’s press enter to launch this command. You won’t receive a response,
4:47
but it worked. You will see that any changes to the controls within Q-Sys is reflected by ‘cv’
4:52
updates reported by the protocol.
4:54
These updates will continue to occur whenever any member control of the Change Group changes
4:59
until the TCP socket connection is broken or you destroy the change group.
5:03
The reason you might want to use multiple Change Groups
5:06
is for when you want to poll different types of controls differently.
5:10
You might not want to poll all controls at the same frequency.
5:13
You might want to poll a meter value every 250ms,
5:17
while you might only poll a Softphone Ringing LED every second or two.
5:22
For these type of needs, just put your controls into different Change Groups
5:25
and set different schedules for each change group.
5:29
If you would like to mark all Change Group controls as ‘dirty’
5:34
and therefore receive the complete list on the next poll interval,
5:37
use the Change Group Invalidate command with the Change Group’s ID.
5:42
The command for that is, you guessed it, cgi 1. Since our Change Group Schedule is running,
5:48
you’ll receive a list of the current values of all controls in the Change Group.
5:52
One other topic that should be mentioned is that you can restrict access to this protocol using the
5:57
Q-Sys Administrator. As long as you have multiple users set up in Administrator,
6:02
you can require that an external control inputs a PIN matching a User Account
6:07
that has External Control privileges. Here, I have disabled External Control access on the default Guest account
6:15
and added an Admin account with the PIN 1234. I’ll save this change,
6:21
which will take effect upon the next new connection from a client.
6:24
Here, I have opened a new Telnet session to my emulated design on port 1702.
6:30
We can type “status get” and receive the expected response, but if we try to change a control,
6:36
let’s use “control set value GainGain 0” and press enter. Aha.
6:43
Doing anything of substance now requires logging in via an account PIN.
6:48
I can type “login Admin 1234” and press Enter, and it tells me I am successful.
6:56
Now I can perform all the usual tasks, as that login is maintained until the TCP socket is disconnected.
7:03
Let’s try our control change again, [csv GainGain 0] … and success.
7:09
One last thing to keep in mind that we mentioned earlier.
7:12
ECP will timeout and close the TCP socket after 60 seconds of inactivity.
7:17
it would be good practice to create a program within your third-party controller that issues a
7:23
simple command such as “status get” every 50 seconds to prevent the port from closing.
7:28
So that’s it for external control. You now have all the tools to control Q-Sys from the outside,
7:34
and make it do your bidding, like your own personal … puppet.
Tips and Definitions
CGPA = Change Group Poll Acknowledge, a confirmation of the information requested
CGPNA = Command to ask for Change Group Poll without receiving acknowledgement
Dirty/Clean: When a change group's control changes, it's 'dirty' and will report its status at next poll, making it 'clean,' and will not report in future polls until it is changed again.