Skip to Content

Register Login

Industry Online Support

Technical Forum

Navigation

SCL: array instances, multiple instance DB

Created by: V4Friend at: 2/7/2008 9:28 AM (9 Replies)

Rating (0)

Thanks 0

10 Entries

2/7/2008 9:28 AM	Rate (0)
V4Friend Advanced Member Joined: 11/30/2007 Last visit: 9/1/2024 Posts: 44 Rating: (1)	Hello SCL-guru's , I have a similar challenge, which I would like a "generic" solution for. In my project I have to control several "array's of valves". Functionality is generally the same: depending on a parameter, one of the valves must open, while all others must close. Of course the position of each valve must be monitored continuously too. I would like to create one FB or FC, which can control the valves. The number of valves actually "connected" to the FB is variable: some may have only 2 valves, other may have "n". Is there a smart way (for instance with an array, or something like a multiple instance DB) to do this?
	Last edited by: CS Moderator at: 07.02.2008 11:23 Splitted and renamed thread It's life Jim, but not as we know it...
Suggestion To thank Quote Answer

2/7/2008 5:16 PM	Rate (0)
Aret Posts: 2348 Rating: (264)	I'd suggest using FB for single valvecontrol. YoucaneasilycombinethemingroupsbyusingGROUP_IDparameter, whichwouldtelltowhichgroupthatvalvebelongs.Valve to open - array of opened valve numbers. Index in this array is group number. Thenusesmthlike IF Valve_to_open[Group_id] = Current_valve_num THEN <Open this valve> ELSE <Close this valve>
Aret Posts: 2348 Rating: (264)
Suggestion To thank Quote Answer

2/7/2008 6:26 PM	Rate (0)
V4Friend Advanced Member Joined: 11/30/2007 Last visit: 9/1/2024 Posts: 44 Rating: (1)	OK, maybe I should have been clearer in my description. The valves are controlled by their own FB, for different types of valves a different FB. Each valve has it's own instance DB. The valve-FB's have a command (IN) and status (OUT). I want a generic way to connect these different commands and statuses to another FB, which controls the group of valves. As I explained, I prefer making only one FB, which can control [1..n] valves. Of course I could use a fixed-length array for these commands and statuses. I consider that "not done" because one would have to assume a "worst-case" scenario for that. Realise that Murphy is always around to mess things up.
	Last edited by: V4Friend at: 07.02.2008 18:27 It's life Jim, but not as we know it...
Suggestion To thank Quote Answer

2/8/2008 1:40 PM	Rate (0)
Aret Posts: 2348 Rating: (264)	i've understood you, but i guess explained not clear enough. Ok what you need is array of BLOCK_FBs of different types. Moreover this array should be dynamic-length. In my opinion that's impossible. So i propose: 1) Insert Group_id and Valve_id variables in each of your instances (so insert it in corresponding FBs) 2) Insert array "Desirable_state" -whichdescribesinwhatpositiongroup!mustbe.(Opened/Closed)andplaceitinsharedDB 3) Insert Control_by_group variable - is valve controlled byDesirable_state or not 4) Inside valve FB create logic - what to do if valve controlled by group and desirable state differsfromactual. 5) Create your main FB (no multiinstance!). For example you need all valves in group 3 to be closed, but valve #3456 must be opened. What you do is: Desirable_state[3] := CLOSED; // CLOSED is CONST "Valve_3456".Controlled_by_group := 0; "Valve_3456".Command := OPEN; // OPEN is CONST and that's it.
Aret Posts: 2348 Rating: (264)
Suggestion To thank Quote Answer

2/8/2008 5:39 PM	Rate (0)
V4Friend Advanced Member Joined: 11/30/2007 Last visit: 9/1/2024 Posts: 44 Rating: (1)	Hello Aret, Thanks again . I understand your solution, but I think it's not really what I'm looking for. It would still require a specific FB for each "group" and that's not what I had in mind. The problem probably comes down to solving the "flexible-length-array", which you say is impossible. Maybe someone else has a brilliant idea?
	It's life Jim, but not as we know it...
Suggestion To thank Quote Answer

2/10/2008 11:57 AM	Rate (0)
V4Friend Advanced Member Joined: 11/30/2007 Last visit: 9/1/2024 Posts: 44 Rating: (1)	OK, of course I cannot get this out of my mind I know some "elegant" solution should be possible here. In CFC I noticed something that is exacly how I would like to solve my problem. There are a couple of "system blocks", like the AND or WAND functions, for which one can enter the necessary number of I/O's in the Object Properties. This way you can dynamically change the number of parameters of the block. Does anyone know how these blocks are implemented and if one could make "user-blocks" in the same way?
	It's life Jim, but not as we know it...
Suggestion To thank Quote Answer

2/11/2008 6:32 AM	Rate (0)
Aret Posts: 2348 Rating: (264)	V4Friend It would still require a specific FB for each "group" No it would not. You can use FC for entering generic logic forgroupactions. Group_id is like foreign key in databases - if you know what i mean.
Aret Posts: 2348 Rating: (264)
Suggestion To thank Quote Answer

2/11/2008 3:11 PM	Rate (0)
V4Friend Advanced Member Joined: 11/30/2007 Last visit: 9/1/2024 Posts: 44 Rating: (1)	Hello Aret (and others of course), I have created an image of the software-structure I envisioned. The Equipment Phase and the FB's for the Control Modules (MOTOR, VALVE) are existing and must not be changed (because they are used throughout the application). The new VLVARR must have a similar structure as the other Control Modules and will be used several times in different EM's. The greatest difference is that it must control [1..n] devices. Hope this helps Attachment ValveArray.pdf (729 Downloads)
	It's life Jim, but not as we know it...
Suggestion To thank Quote Answer

2/11/2008 3:53 PM	Rate (0)
Aret Posts: 2348 Rating: (264)	Well,ifchangingDBsMOTORandVALVEarenotpossiblethenmysolutiondoesn'twork. I've done all i could - maybe somebody has another method.
Aret Posts: 2348 Rating: (264)
Suggestion To thank Quote Answer

2/12/2008 8:29 AM	Rate (0)
V4Friend Advanced Member Joined: 11/30/2007 Last visit: 9/1/2024 Posts: 44 Rating: (1)	Hello Aret, Thank you for your ideas. It's really nice if someone tries to help you I think for now I will use a fixed number of IN and OUT parameters for the ControlModules, though I don't really like that. And for others: is there really nobody with an idea on solving the "dynamic-lenght-array" for parameters?
	It's life Jim, but not as we know it...
Suggestion To thank Quote Answer

|

Share this page:

Share this page on...

Follow us on