Lua Looping Script

donb9261 · 2016-09-17T09:01:43+00:00

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Lua Looping Script

donb9261

How can I have a Lua script continuously loop. 

Example:

I am building a system that will monitor the state of external switches from devices. In order to catch the state change I would need to create an event loop that every so often would check the state. If the state changes then do something. 

I may want a sequence of things to happen if the state changes. Then return and the loop continues. Like scan. 

I may need several loops all running simultaneously watching various things. Returning variables etc.

I have never run Lua as server app. But know Lua quite well. I use it now for controlling industrial machines like a PLC.

Any help is appreciated.

jenders

On Friday, September 16, 2016 at 6:01:43 PM UTC-7, Don Bozarth wrote:

How can I have a Lua script continuously loop.
Example:
I am building a system that will monitor the state of external switches from devices. In order to catch the state change I would need to create an event loop that every so often would check the state. If the state changes then do something.
I may want a sequence of things to happen if the state changes. Then return and the loop continues. Like scan.
I may need several loops all running simultaneously watching various things. Returning variables etc.
I have never run Lua as server app. But know Lua quite well. I use it now for controlling industrial machines like a PLC.
Any help is appreciated.

This is a great question but it may be better answered by a general purpose Lua mailing list. Is there some interaction you're planning with OpenResty in particular?

ggroups

You can use nginx.lua timers for that. Please have a look into the documentation, it is really well documented. Also look at https://github.com/openresty/lua-resty-upstream-healthcheck for an example.

On Saturday, September 17, 2016 at 3:01:43 AM UTC+2, Don Bozarth wrote:

How can I have a Lua script continuously loop.
Example:
I am building a system that will monitor the state of external switches from devices. In order to catch the state change I would need to create an event loop that every so often would check the state. If the state changes then do something.
I may want a sequence of things to happen if the state changes. Then return and the loop continues. Like scan.
I may need several loops all running simultaneously watching various things. Returning variables etc.
I have never run Lua as server app. But know Lua quite well. I use it now for controlling industrial machines like a PLC.
Any help is appreciated.

donb9261

Actually no. Lua is not the issue here. Lua can do this kind of function very easily. The question relates to running this type function where I continually loop a program every 1ms to check the status of physical world switches and have action callad against the switch state.

On Friday, September 16, 2016 at 8:35:21 PM UTC-5, Josh Enders wrote:

On Friday, September 16, 2016 at 6:01:43 PM UTC-7, Don Bozarth wrote:
How can I have a Lua script continuously loop.
Example:
I am building a system that will monitor the state of external switches from devices. In order to catch the state change I would need to create an event loop that every so often would check the state. If the state changes then do something.
I may want a sequence of things to happen if the state changes. Then return and the loop continues. Like scan.
I may need several loops all running simultaneously watching various things. Returning variables etc.
I have never run Lua as server app. But know Lua quite well. I use it now for controlling industrial machines like a PLC.
Any help is appreciated.

This is a great question but it may be better answered by a general purpose Lua mailing list. Is there some interaction you're planning with OpenResty in particular?

donb9261

bjoe2k4,

I looked at it. It seems like this could work except this is a configuration file. So, what you are saying is I would need to create a new configuration that spawns this worker? I may 500 of these working and then one checking the 500. Would one need 500 config settings? Please excuse my ignorance. I am a robotics engineer. I am learning servers. :-)

On Saturday, September 17, 2016 at 3:38:37 AM UTC-5, bjoe2k4 wrote:

You can use nginx.lua timers for that. Please have a look into the documentation, it is really well documented. Also look at https://github.com/openresty/lua-resty-upstream-healthcheck for an example.

On Saturday, September 17, 2016 at 3:01:43 AM UTC+2, Don Bozarth wrote:
How can I have a Lua script continuously loop.
Example:
I am building a system that will monitor the state of external switches from devices. In order to catch the state change I would need to create an event loop that every so often would check the state. If the state changes then do something.
I may want a sequence of things to happen if the state changes. Then return and the loop continues. Like scan.
I may need several loops all running simultaneously watching various things. Returning variables etc.
I have never run Lua as server app. But know Lua quite well. I use it now for controlling industrial machines like a PLC.
Any help is appreciated.

donb9261

Example of a check of the state. I use this in my current application but it runs locally on a PC not as part of a server.

[mc.ISIG_INPUT1] = function (state)

if (state == 1) then

CycleStart()

--else

--mc.mcCntlFeedHold (0

end

end,

On Saturday, September 17, 2016 at 3:38:37 AM UTC-5, bjoe2k4 wrote:

You can use nginx.lua timers for that. Please have a look into the documentation, it is really well documented. Also look at https://github.com/openresty/lua-resty-upstream-healthcheck for an example.

On Saturday, September 17, 2016 at 3:01:43 AM UTC+2, Don Bozarth wrote:
How can I have a Lua script continuously loop.
Example:
I am building a system that will monitor the state of external switches from devices. In order to catch the state change I would need to create an event loop that every so often would check the state. If the state changes then do something.
I may want a sequence of things to happen if the state changes. Then return and the loop continues. Like scan.
I may need several loops all running simultaneously watching various things. Returning variables etc.
I have never run Lua as server app. But know Lua quite well. I use it now for controlling industrial machines like a PLC.
Any help is appreciated.

donb9261

Sorry,

Better example:

SigLib = {

--Enable

[mc.OSIG_MACHINE_ENABLED] = function (state)

machEnabled = state;

end,

[mc.ISIG_INPUT1] = function (on_off)--mc.ISIG_INPUT1

if( _on_off_==1 ) then

-- On

else

-- Off

end

end,

[mc.ISIG_INPUT2] = function (state)--mc.ISIG_INPUT2

if( state == 1 ) then

-- On

else

-- Off Call A function here if you wanted

end

end,

--The user can add additional Signal events if they wish by following the same format as above.

--[SIGNAL NAME] = function(state)

--if(state is active) then

-- do active code

--else

-- do inactive code

--end

--end,

}

On Saturday, September 17, 2016 at 3:38:37 AM UTC-5, bjoe2k4 wrote:

You can use nginx.lua timers for that. Please have a look into the documentation, it is really well documented. Also look at https://github.com/openresty/lua-resty-upstream-healthcheck for an example.

On Saturday, September 17, 2016 at 3:01:43 AM UTC+2, Don Bozarth wrote:
How can I have a Lua script continuously loop.
Example:
I am building a system that will monitor the state of external switches from devices. In order to catch the state change I would need to create an event loop that every so often would check the state. If the state changes then do something.
I may want a sequence of things to happen if the state changes. Then return and the loop continues. Like scan.
I may need several loops all running simultaneously watching various things. Returning variables etc.
I have never run Lua as server app. But know Lua quite well. I use it now for controlling industrial machines like a PLC.
Any help is appreciated.