Modbus RTU PLC selection

We are looking for the most cost-effective, highest quality PLC for use with an existing Modicon system (Modbus Plus or Modbus RTU communications). This will be a low I/O count (25 discrete out/30 discrete in/4 analog out/8 analog in) and can either be 120 vac or 24 vdc powered. Any suggestions from the group?

See link: Controlmicrosystems SCADAPak Series.
Reliable and very,very good support.
http://www.controlmicrosystems.com/

Thanks Mickey, I will contact the local rep to discuss pricing and availability.

Cogen,

I will offer a biased option in that it is our company's product.

The Elite-2000 www.entertron.com/elite.htm

The I/O requirements are well within the controllers range. A configuration of 32 / 32 Digital I/O and 8 AI / 4 AO would be the configuration. The controller is expandable to 64/64 and 16/16 total.

The digial I/O is solid state with built in optical isolation, fusing and noise suppressions. The analog I/O can be ordered in just about any combination of configurations on the same board. (Voltage, current, Type K thermocpouple, RTD, millivolt)

Programming software is included with the Elite-2000. We have also placed a 7 year warranty on the controller, free from manufacturing defects.

The protocol would be ModBus RTU. I would be under the impression that if it is going to be working with an existing Modicon controller that the new controller would be a slave to the Modicon unit.

If you have any questions, feel free to contact us through the email or telephone number that are posted on our web site.

God Bless,

I've had good luck with both Control Microsystems and AutomationDirect.com (ADC). The ADC is less expensive, particularly the DL-05 nd DL-06, and does Modbus RTU. The Control Microsystems has more comm ports, and it's ladder logic is almost identical to the old Modicon 984 ladder programming.

Look into Wago Programmable Fieldbus controller. I have not used them, but I am planning to early next year. I have been working with the demo software and it seems fairly easy to use. They do not fit the standard PLC form factor, but they are powerful and inexpensive. Also, you can program them in Ladder Logic if you like.

Regards

I'll 'third' my reccomendations for Scadapacks.

we have used probably 100+ of them and they are super reliable, easy to program (free software!) and come with tons of comm ports.
they are also temperature rated to below freezing.
If your looking for inexpensive, they do 4 or 5 models from fixed IO and less commports to expandable with onboard radio.
Theres usually something that fits well into what you want to do.