I get the feeling that an IO subsystem based on ASI would be considerable cheaper than alternative bus systems I could mention.  Typically systems have a number of distributed IP6x “master” bus nodes located at strategic points around the machine with M8/M12 or valve banks radiating off or bus interfaces connected via a backplane to M12/M8 nodes.

Although these systems involve less cabling and therefore less labour than a hardwired system they are still fairly expensive in hardware terms.

What I’m wondering is has anyone done any sums, ideally comparing hardware and labour costs between the three systems - 1. direct wired using multicore cables connected to M12/M8 distribution blocks, 2. BUS system (such as Murr CUBE67 or Siemens ET200) 3. ASI based system.

I’m in the process of producing a control system for a medium sized packaging machine handling 240 products per minute, involving 11 servo axes and 5 speed control inverters, a press, a printer, heaters, hot-melt, slitter knives, vision system QC, collation etc.

MCR

Hi MCR
A good few of the items you have listed won’t go on AS-interface. Maybe Siemens has done all 3 types of calculations. SIGMAPI as a System House should have a good idea.
I shall forward your request.Version 3 now supports HMI and higher density I/O, invertors and Speed control would normaly be at a different level. 
Regards Derek Lane

Hi Derek,

Thanks for your reply. Just to be clearer I’m only expecting ASI to handle I/O, not servos or inverters or HMI - these would be via Profibus or flavours of ethernet and proprietary buses such as Sercos or DriveCliq.

Thanks,

Martin

Hello Martin

I did the sums once - about 15 years ago - on systems comprising only digital I/O, when we were trying to get Ford Motor Company to accept AS-I. It was new technology to them at that time.

My calcs were AS-I (Generation 1 then) against Interbus (their then preferred fieldbus). The sums showed 50% savings. I included hardware costs and reduced connector-assembly wiring time (over interbus). The operation was a success - and we have been using AS-I on all our equipment ever since. Several of our OEM colleagues in the automative industry, having initially sneered at AS-I, are now using it themselves.

There are other savings apart from hardware and wiring time. The biggest one, that you can’t really put a price on, is the saving in overall installation time i.e. your equipment is wired and ready to test more quickly. You can ship earlier, and get paid earlier! The level of skill required from the electricians is lower.

Engineering costs are reduced - for our inital installation, we had 150 sections of automation, all at least slightly different. With AS-I, the control panels were all identical - all differences were in the configuration of the field items. This made the drawings very easy to produce. We used AS-I I/O and AS-I motor starters - also inverters with AS-I interfaces.

We are still big AS-I fans - I have seen no other system than comes close to it in terms of simplicity and minimal programming overhead.

I tend NOT to use AS-I for valve banks - most of the systems I have seen use a whole node for one solenoid or maybe a pair. So we still have 2 bus systems - AS-I for digital (and now analogue) I/O, Profibus for drives, valve banks etc.

Hope this helps

Jon

The another savings apart from hardware and wiring time. The biggest one, that you can’t really put a price on, is the saving in overall installation time i.e. your equipment is wired and ready to test more quickly. You can ship earlier, and get paid earlier! The level of skill required from the electricians is lower. You can use this selection for solve your query.