Looking for a small PLC

[dss]

We are searching a small PLC to integrate in a 3U high (132 mm) / 19 inches wide (482 mm) rack space. This space must include the space for thermal dissipation and the cabling. We reviewed many options of many suppliers (Rockwell, Schneider, Siemens, RTP, Hima, Omron, Mitsubishi, Pilz, Wago, Phoenix contact, Gefran, Gilogik, IDEC, ABB, Honeywell, Saia-Burgess Controls, GE Fanuc, Rexroth Bosch Group, Hitachi, IMO, Omniflex, Festo, Jokab, EADS/Racal, VME solutions, Macq Electronique, B&R Automation, National Instruments) and we didn’t find anything. Thanks for you help and propositions of solutions. The needs in inputs/outputs are the following: 3 RS485 independent channels, 2 Ethernet channels (or 1 with a switch), 7 binary inputs (24VDC), 6 binary outputs (free contacts, 1 NO + 1 NC each), 3 analog outputs (4-20mA, 12 bits minimum). It’s for an industrial use and we would like to have access to qualification information: norms, levels and criteria. Main expected norms are RCCE-2005, CEI 60439, CEI 60068, CEI 61000 and NF EN 55022. And then, we would like the solution has a correct life time cycle: about 8 to 10 years of stability for hardware and software embedded, about 15 to 20 years of stability for the function. Thank you.

[Mike Dyble]

The only other one that comes to mind that is not on your list is Direct Logic, look at www.automationdirect.com

[dss]

Thank you. But this PLC is not responding due to thermal dissipation : a minimum clearance of 3” (76 mm) is required up and down of the PLC.

[paulengr]

I've run into this before. One of the basic problems is the form factor. Most PLC's are designed around electrical cabinets which tend to be vertical, not horizontal. So they are compressed in the opposite direction from what you desire, as opposed to telecom equipment which is meant to be compressed in the horizontal dimension and rack mounted. Your Ethernet requirement is simple. A switch will take care of this requirement and there are many good ones out there (Hirschmann, Sixnet, etc.). I would suggest in the PLC's that I'm aware of that you look closely at the controlmicrosystems.com SCADApack PLC's, and within the Allen Bradley line, the Micrologix and CompactLogix series, specifically the L23x series which are "brick" style PLC's. They all hit very close to the vertical dimension. I suggest the Control Micro systems only because they aim for the utility market which usually tends to go rack mount with their equipment, too. 3U needs 133 mm high by 479 mm wide by 671 mm deep. The sticky issue is the 133 mm vertical height limit. With the L23x, it is always drawn in the vertical format and it is 132 mm high, but requires 50 mm of clearance on either side for thermal dissipation. Depth is a comfortable 87 mm. Try contacting AB though. I believe you can mount it horizontally (on it's back). In which case you have plenty of clearance. You'll just need to mount everything on a slide-out style rack if you need to work on it, and I'd suggest maybe even going to the L33 or L44 family simply so you can get RTB (remote terminal blocks) and mount your terminal blocks on a wall at the back instead of having to fish wires way down inside the bay. You could do something similar with the Micrologix series. Heat dissipation on these things is extremely low so I wouldn't even be concerned about it. The Micrologix 1100 and 1400 both come with a single Ethernet port which fits your requirements.

[BobLfoot]

Since you are in a telcom/rack environment have you considered some of the PC based I/O systems which run as PLCs. First couple examples which come to mind are Entivity VLC, Think and Do, Rockwell Softlogix 5800. You can get PCI rack mount units which will accept your DI/DO signals and ANA_IN/ANA_OUT signals. Adding 2 or 3 NIC's should not be an issue. I know you probably want a "true PLC" but you might want to look at "PC based PLC type controls" as an option.

[aggattapauer]

Hi dss, See Schneider Electric M340 372 mm length (8 slots) 100 mm highth 160 mm width 2 ethernet port (modbus TCP) 1 serial port 232/485 (modbus / ASCII) For serial lines you might consider to use gateways 485/ethernet salut

[kaiser_will]

Consider Beckhoff, more specifically their Bus Terminal - Fieldbus line. http://www.beckhoff.com/

[Mickey]

These have lots of communication options. http://www.controlmicrosystems.com/

[dss]

Thank you all for your contribution. And does anyone know the solutions VIPA?

[JesperMP]

To my opinion, your specs are most closely matched by Beckhoff. Beckhoff bus terminals are 100 mm high. I couldnt find the required space above and below, except for terminals that have a high thermal load - these require 35 mm above and below. As none of your terminals have a high thermal load, I believe that half the space above and below is OK. You can turn it around and try to calculate the temperature rise based on thermal dissipation. If you can keep the temperature below 55 degr. C you should be OK. Wiring would not be pretty, but that goes for any other solution with such small available space. Similar terminals from Phoenix Contact, Siemens and AB are physically bigger. AB and some others also have petite brick PLCs. But I dont think they can match the requirement for 3 serial ports. Possible exception is Siemens S7-200 that have serial and ethernet expansion modules - however, I am not sure if it can be fitted with that many expansion modules. Vipa 200V could be the only other PLC that is small enough and also has the required functionality. One pitfall is if you have special requirements for what protocol you want to use on the serial ports. As to software lifecycle, then I guess that both Beckhoff and Vipa have reasonably acceptable softwares. Beckhoff follows IEC61131-3 which is the only standard worth mentioning. Vipa is Siemens S7 compatible, and Siemens S7 is practically ubiquitous - being a defacto standard despite proprietary. Edited December 16, 2008 by JesperMP