Safety PLC manufacturers


Thread Starter

Arturo Arévalo

Hi, does anybody know about manufacturers of safety plcs? I only found AB and it seems that manufacturers like siemens and ge only have redundant options not something as specific as the guardplc that AB offers.

thank you.

Take a more indepth look at Siemens, depending on your requirements, Siemens does meet safty standards with the PLCs (S7 & S5), I/O, Profi-Safe and products like light curtains...
Siemens currently has a safety solution with the S7-400F for large applications. They are scheduled to release the S7-300F in June to compete with the A/B Guard 1200.
The only ones I am aware of are Pilz, and AB. All the others I am aware of are just redundant. The Pilz PC has an interesting feature, dual processors from different manufacturers solve the ladder, then compare results, just in case there is a processor design problem. I've never used one however.

Gabriele Corrieri

I know that PILZ sell a *very* guardplc, but I not know it's web site. Try to search on Gongle or another search engine.

Best Regards

Gabriele Corrieri

Michael Booker

There are several companies out there that make Safety PLC's, but be careful. You need to make sure that the PLC you choose meets the requirements of your application. Are there any SIL requirements in the specification? This can be a MAJOR gotcha if your not careful. General purpose PLC's (i.e., PLC-5 and SLC) do not meet Safety PLC requirments. However, Allen-Bradley is now offering the GuardPLC 1200, which has fixed I/O and the GuardPLC 2000 which is more flexible. These Allen-Bradley systems are pretty new though. We may give these a try after they have been out a while. We have had great success using the HIMA safety systems. You can meet SIL 2 requirements with a simplex I/O system. Again, if SIL requirments must be met, then the SIL requirement must be met from the input device, to the logic box, to the output device (the whole
loop). I would take a look at HIMA and Allen-Bradleys new offerings.

Stephen Thomas

There are lots of different vendors and products. AB is a relative newcomer to this field. Check out Triconex ( "": ), the Siemens-Moore QuadLog
( "": ), ABB TriGuard ( "": ), Trusted ( "": ). In my opinion, they are all pretty similar, and the brand of safety PLC is much less important than the quality of the SIS
design/operation/maintenance cycle that is used to implement it.


Siemens definitely has a Safety system, actually pretty soon two of them: S7-400F and S7-300F
You are correct the S7-400F is actually an S7-400FH, but the H is optional, you can also use one CPU and get a regular or F system out of
it. With FH you would both be Safety and Redundant. The S7-315F is going to be released soon.

Please do define "safe PLC", since there are so many interpretations of that.

On a broad definition, I would consider as "safety PLCs" some products by HIMA, Siemens (ex-Moore) Quadlog, all the TMRs (August, Triconix, Triplex), GE's "GMR", Yokogawa, and so many others.


Vitor Finkel
[email protected]
P.O. Box 16061
22221.971 Rio de Janeiro Brazil
Tel (+55) 21 2285-5641
Fax (+55) 21 2205-3339
Well, it is not a PLC but just have a look at "": ,if your I/O numbers are low. They have a failsafe system (the highest category, category 4) which is
programmable in some ways. It is too much cheaper than a failsafe PLC and somehow programmable (digital) and they have an OP also.
AB's offering is a recent acquisition and is not as full featured as some. It was acquired to fill a hole in ABs portfolio. I believe that the two versions of the guard plc are primarily intended for application to machinery safety.

Both GE and Siemens have proper certified safety system PLCs. These PLCs are used in ESD systems in the oil, gas and chemical industries.

Siemens refer to them as Failsafe PLCs. These are TUV certified for use to at least SIL3 (subject to application and programming). There are various versions S5-95F, S5-115F. The S7-400 can be used with redundant I/O and special application software to create failsafe systems.

GE Fanuc has similar products but I am not familiar with them.

The big boys in Safety PLCs are Triconex ( "": ) and ICS
Triplex ( "": ).

Pilz ( "": ) also have safety PLCs.

There is a good list of PLC manufacturers at .
For a more complete insight into Safety Instrumented Systems and the scope of the requirements, refer to ANSI/ISA 84.01 (A standard published several years ago by ISA and available from their website: "": ) and
IEC61508 (The International standard)

Michael is correct that all components of a Safety Instrumented Function (SIF) must be considered in making a Safety Integrity Level (SIL) calculation. For guidance on what this entails visit "": .

For insights on methods to increase reliability of field devices (and therefore safety) of field devices go to the Safety Related section on the
Moore Industries website: "":

Bud Adler
Director, Business Development
Moore Industries-International, Inc.
The Interface Solution Experts
[email protected]
Office: 407.324.9389
Cell: 407.353.2727
Fax: 561.828.2232

Johnson, Eric

Arturo, yes there are many more than AB. The list below is just off the top of my head, I beleive all of these are TUV certified to SIL 3.

Siemens - Moore Quadlog
( "": )

RTP ( "": )

Honeywell ( "": )

Triconex ( "": )

ICS Triplex ( "": )

Pilz ( "": )

ABB ( "": )

HIMA ( "": )


Eric Johnson


Berthold Ruhbach

Dear Michael,

you can also achieve SIL-3 with single CPU module and single I/O.

The new AB safety PLC are in fact developed and manufactured by HIMA. HIMA has an OEM agreement with Rockwell.
> Yokogawa ProSafe PLC (Tuv6), Hima PLC, Triconex PLC, HoneyWell PLC, etc.

Is there a PLC that meets (At minimum, the new PLC shall meet
the safety integrity level (SIL) 3 standard per IEC 61508.)

It would also need to take two encoder inputs and compare the ratio between the two. if the ratio changes it would set a contact. We are trying to measure the speed of a hoist motor and the drum. If they change it means something broke.

Thanks in advance