Using the Eco Ac500 PLC as Remote I/O for DCS controller
I do have a project that contain 84 remote location
I need to use the eCO AC500 PLC to act as Remote I/O
so I need to use 84 AC500 controller
what is the convenient DCS controller to connect to all these AC500 ?
is there is any controller that can support such number of remote I/O's ?
if not what is the alternative solution ?
the max distance between the controller that be 500 meter
what is the better communication protocol?
is there is any other software/ hardware required?
thanks in advance
Voted best answer
Architecture/image of your requirement will help more.
(i)You need 84 remote stations at field to control and send data to DCS system located 500 m far ? or (ii)you need to control from DCS and need 84 remote I/O's at field to collect data and send to DCS? And what is total I/O count ?
Incase of first option you need to use controller at field, I am not expert of AC500/eco AC500, but I know you can communicate between AC 800M, AC 9/8/700F and AC500 over MODBUS TCP would be good option for distance vs data transfer requirements, also you can use Eth send/recieve between freelance and ac500 controller check one of the App associated here.
Incase of second option you can use S500 i/os over profibus but looking to your distance requirement you ned to optimise with speed. check distance/speed
In summary you can use system 800xA or Freelance DCS system to fullfill your requirements. There are lot of factor to be considered in deciding with which one is best suitable/fit in your requirements.
Also recommend you to get in contact with local ABB sales colleague. Can you update your location detail in your profile ?
You need to consider a few things.
The Com1 only reaches 50 meters. So if the cables lengths are more you will need some Seriel to seriel converters(ILPH RS485 to RS485). They can also be used for galvanik seperation so you could reach your 500meters.
The RS485 system for modbus RTU supports only 31 slaves, so you will need some Cpu's as middle men collecting the data from fx 10 slaves and resending it to the master.
The RS485 protocoll supports up to 1200meters at 19200 baud so that shuold cover your needs.
I would think that any DCS system that supports Modbus would be usable. But you could consider using one of the larger cpu's of the AC500 system such as PM590 to PM592. They are a cheaper solution I would think and you would only need 1 programming software.
This does not sound like a good idea. There are some pretty serious problems that could potentially occur. The AC500 is a very good PLC but it is not designed as a remote I/O system for another DCS controller and you need to fully understand how a Modbus or similar link will affect I/O cycle times and latency in your application software.
For example, running a PID loop where the Analog I/O is in an AC500 and the PID controller is in your DCS ( eg an AC800 ) will likely run into serious problems because your I/O scanning and your PID control loop is not synchronized properly. If your link between the AC500 and your DCS is slow, your I/O data could be several seconds out of date by the time the PID controller executes. Worse, on some scans the delay might be small and others much larger, making PID control very unstable. Similar issues can affect digital IO which may be even more sensitive to timing problems.
Of course, if your control is done directly in the AC500 PLC, then this is not a problem. But programming 84 AC500 controllers sounds like too big a project. Perhaps you would be better to use AC800M with S800 I/O lite modules over profibus. ( Lite is much cheaper than full size S800 modules ) and a Profibus I/O system can travel large distances and support a large number of I/O stations and channles.
thanks every one for your inputs
the aim of using the AC500 (84 controller) is to control typical 84 process location (chambers )
the controller will be done in the AC500 (the control program and variable setting will be identical )
the DCS system will only collect data for the purpose of monitoring