Remote racks

[DLTimmons]

I don't know about less painful!!

This is a large conveyor system that has three seperate areas that are interconnected. Commands are sent by a PC running a VB project over one rs 232 line, only one command can run at a time but it might span two of the three section or a fouth unit that is a ASRS crane on a separate RS-232 that has to be cordnated with the conveyors. At this point there are 40 VFD's 4 that will be on elevators that position off encoder feed back. over 140 sensors and a few outputs and 4 bar code scanners. I will be tracking over 70 racks that will be stored in the system plus up to 18 rack in transition. That will be a lot of data that has to be shared between CPU's.

It looks like I would have to use Modbus or a combination of Modbus and Peerlink. If I read correctly peerlink could not handle just one of the barcode scanner data. Looks like I would have to have 4 CPU one as a master that communicates with the PC and controls over all opertions and three more, one for each section.

This will be a good test for the Do-More CPU.

[BobO]

Sounds like a fun app. Seriously...I love stuff like this.

Peerlink allows the publishing of a total of 16 blocks of 16 words each. A single Peerlink station can publish 0 to 16 blocks. The data is published at about 10Hz.

So...distributed vs centralized. Great fun. In developing the Do-more control engine, I became a great fan of layering services. Creating well-defined interfaces that hide the details of how something is done and reduce it to an abstract and asynchronous 'do this', 'are you done yet', and 'how did it go' type of interface. I have many layers of state machines operating low-level objects. There is a minimum of data passing and the system is quite robust.

Not knowing the details of your app, I'm not sure how I would approach it...but...my general design methodology would likely have me looking for ways to bury the details and minimize the data flow, rather than sending all the data up to a single top level controller. I would generally view the top level guy as the conductor...he doesn't play a single instrument, he just guides those who do.

We would love to follow your progress though. Please keep us up to date!

[DLTimmons]

Bob

I see were your coming from. Just have figure a few things out at this point nothing set in stone.

This system takes racks of small parts bins and position them for a ASRS crane to store and keeps empty racks stored till they are need for withdraws. Part of the deposit is reading a barcode label contains a bin ID that is sent to the server that then sends the command to the crane to pickup the bin and store it. After all bins are stored from that rack the rack is sent to a store area in the conveyor systems till need for a withdraw. Then withdraws are handled by the crane depositing a bin into a rack that is waiting in a special locaion on complete of the cranes part a command is sent from the server to move the rack out for pickup and a empty rack is place back in it place for the next bin.
There are 7 levels of conveyor the lower is for deposits to the crane and rack can accumlate on this level if the come in fast then the crane can get to them. the second level is will be kept open for withdraw to move out on. The other 5 levels will be store of racks. Levels will be connect on each end by elevators and there are two side. the VFD are used to reduce shock load on the conveyor chains and to handle acculation by stopping and starting the conveyor as each rack comes on or goes off. there will be capicty to store 70 racks. I will have to keep track of how many and were they are.

I plan on using the new Ctrio2 in way you might not have thought of to control the elevator. Will let know how the works out. Might be a good app store here