program advice please?

Hi All,

Just starting out on a project, boss is starting to release funds to get the stuff in

This is a retrofit control to an existing 11 tank solvent mixing rack.

Basically I am to be monitoring 11 small tanks for level and top them up with a mixture of solvents and/or water. The mix in each tank will be one of 20 combinations/proportions of 1 or 2 of 6 solvents and/or water. The total batch of a top-up will be 10 litres.

Due to existing pipework/valves, only one tank can be filled at a time, only one solvent can be dispensed at a time.

Simple level switch in lower section of each tank (via EX Barrier). 30+ valves for solvent filling (1 for each solvent into flow meter, 1 for each tank out of flow meter. Duplicated for water also, and a outlet to a bucket)

Operator to select recipie for each tank on HMI (Telemec Magelis VGA screen). System to monitor each tank for low level (<3 Litres) and then refil with the selected mixtures.

PLC is to be ML1100 plus 2x 16 i/p and 2x16 o/p with ethernet link to the HMI 40M away.

2 flow meters; one in solvent leg and one in the water leg. Only 1 of these is/can be active at any time due to the way it is piped. Therefore I am getting away with the single HSC and using a relay to switch either of the flow meters to the HSC input.

This has allowed me to use the ML1100 and get ethernet comms at a reasonable total cost, going other AB routes to get Ethernet (for the 40m between PLC and HMI)needed either SLC5/05 or the NET-ENI(W) adaptor. DH485 added cost for each node, well 2!

The SMTP messaging looks a great bonus too; to be a later addition to email us (maintenance) on a pump flow fail detection.

My initial thoughts are:

What is the prefered way to do recipies? Would you do it on the HMI, and write data for each tank to the PLC; Or better to store the recipies on the PLC and just select which one with the HMI?

Because only one tank can be filled at a time I need to work a couple of clever (for me!) little things.


I have not started writing anything yet as I am trying to flow chart the whole operation first.


I dont want the program written for me, just a couple of pointers so I start in the right direction!

BTW: Not used FIFO or Sequencers before.

I'm a big fan of HMI Recipe functions. and with 11 tanks it sounds like you have potential variability.
My recommendation is to use the HMI as the recipe and have a physical selector switch to switch between say 15 selections.

GE_Plcs_are_Love said:

I'm a big fan of HMI Recipe functions. and with 11 tanks it sounds like you have potential variability.
My recommendation is to use the HMI as the recipe and have a physical selector switch to switch between say 15 selections.

Click to expand...

Sorry, can you clarify?

timbo_uk said:

Sorry, can you clarify?

Click to expand...

So do you mean a 15way selector switch for each of the 11 tanks? That would need massive I/O; I was thinking of just using the HMI to select the recipie for each tank.

Anyone elso got any pointers etc please?

Not really gonna help your problem here - but for your information
you can buy a 15 (or 16 if you count zero) binary selector switch
that uses only 4 inputs . You then decode the binary inputs.

ah Bradford lads - you gotta love em

Goody said:

Not really gonna help your problem here - but for your information
you can buy a 15 (or 16 if you count zero) binary selector switch
that uses only 4 inputs . You then decode the binary inputs.

ah Bradford lads - you gotta love em

Click to expand...

Nowt wrong wi Bradfud lads tha' knows

That is still another 44 inputs on an ML1100; way over the spares; I am allready using almost the max I/O that I can with this PLC, it just fits nicely into budget especially with its features.

I am a little confused (not because I am a Bradford lad) as I was under the impression that the idea of an HMI was to reduce I/O requirements on a PLC and to add extra functionality?

Regards

Tim

I would store the recipies in the plc and then use a multistate push button on the panel view to view the recipies or change the recipies.

My two censt worth

IF you decide to store the recipes in the PLC remeber that if you restore your PLC program form a previous saved version you will overwrite any recipe changes that have been made since the plc program was saved. The advantage of saving them in the PLC is that if your HMI let's it's magic smoke out then you still have your recipes. If it was my prject I would keep recipes in HMI and also another copy say on CD or File server (out of harms way) and use the HMI to download all recipe parameters to PLC when required

Dua Anjing said:

IF you decide to store the recipes in the PLC remeber that if you restore your PLC program form a previous saved version you will overwrite any recipe changes that have been made since the plc program was saved. The advantage of saving them in the PLC is that if your HMI let's it's magic smoke out then you still have your recipes. If it was my prject I would keep recipes in HMI and also another copy say on CD or File server (out of harms way) and use the HMI to download all recipe parameters to PLC when required

Click to expand...

Thats the bit that was getting to me; ie whats best!!!

So is the opinion that I would have data tables in the plc simply hold the recipe parameters for each tank. These are written too by the HMI every time the product is changed.

The recipie for each tank would be an array of 6 products and the amount in litres of that product, eg:



I intend (as a double check?) to also write a 16 character text description (of the recipie used) to the data area of the plc; this would be read back by the plc and show this on the "tank" on the screen of the HMI.

The data above would be in the HMI, one row of this will be sent to each tank data potion when selected. There will also be a row of "OFF" with all zeros.

Think I am on the right lines here!

Thats' the way that I would go but after teh others have finished voting (and sleeping) they will chime in with other idea's and suggestions. I would have a screen that would let the operator see all the ingredients in the recipe he/she has chosen prior to downloading it.
eg:
Step 1: step is operator selects recipe from a pull down list.
Step 2: Show operator all ingredients and amounts along with something like "Are you sure ?" maybe even show existing (last used) recipe so op. can compare.

What HMI have you decided on ? I guess a lot of HMI will be able to show recipe data in some form of table that would make operators selection easy.

Dua Anjing said:

Thats' the way that I would go but after teh others have finished voting (and sleeping) they will chime in with other idea's and suggestions. I would have a screen that would let the operator see all the ingredients in the recipe he/she has chosen prior to downloading it.
eg:
Step 1: step is operator selects recipe from a pull down list.
Step 2: Show operator all ingredients and amounts along with something like "Are you sure ?" maybe even show existing (last used) recipe so op. can compare.

What HMI have you decided on ? I guess a lot of HMI will be able to show recipe data in some form of table that would make operators selection easy.

Click to expand...

Telemecanique Magellis XBTGT4330 (sat above my bench ready and waiting!)

Just got to get my head round the help file now:

http://www.send2deliver.com/deliver.php?5a91ef13b5f14afcc71eb15675e38ef7

had quick look thru the help file (nearly finished for the day) looks like it will do it very nicely, I will try and give it a good read tomorrow.

Cheers, appreciated!
I finish in an hour too, must go finish a job now!!!

and what happens if the PC or HMI fails?

i work in an industry where failsafe/single failure is prioritized as high as safety

I would drive the system via the HMI as others have already said.

Have a selection page where the recipe is selected. I do similar thing on CIP systems.

Is there any priority over which tank is allowed to fill first?

As far as failure is concerned, it is simply 'tough' if the HMI fails... that is life, and hopefully you carry spares at your factory.

If it starts to look a bit hairy maybe you could add OPC or similar to provide an external database to allow for ease of recipe editing etc.

Good Luck, Cheers