Flex EX I/O

[KCRider]

Anyone have any experience implementing Allen Bradley's Flex EX I/O systems? I have a Zone 2 application. The Flex EX will be located in a safe area and wired to instruments that are located in the field. From what I can deduce from AB's documentation, I should be okay with wiring the I/O modules directly to the field devices. Any additional input would be appreciated.

 

[bayeibrahima]

Hello sir
I'm not experienced on flex I/O laying;just a notice
I think, if you are working in a noisy area you should use fiber optic cable between your plc and the I/O Heads; then signals from instruments will be transmitted to the plc without any troubles
Best regards

 

[iant]

I do not know what Zone 2 is, however if I assume it may be an intrinsicaly safe area, I would suggest that you get specific approval before using any devices in these areas

 

[JeffKiper]

Are you suee of the area class ? Zone 2. There us a huge difference between the 2. Gas and dust.
What plc are you using? What I/O are use using? I have found some I/O is fine for class 1 div 2 installations. There are other brands of I/O out there that have better price points.

 

[KCRider]

Thanks for your inputs. The process area where the instruments will be located is indeed a Zone 2 area. Zone 2 is equivalent to Class 1 Division 2. We're dealing with flammable gases. The main PLC is a Controllogix 1756 series processor. A Controlnet adapter is being used for connection to the Flex I/O bus. The Flex Ex I/O is located in the same enclosure as the main processor, and these components are located in a safe area (MCC room). The field wiring will be brought into the safe area and terminated on the Flex Ex I/O.

 

[JeffKiper]

Do you need the intrinsically safe classified EX or have you looked at what the 1756 io is rated for. They may be rated class 1 div 2. You will have to look at that option.

 

[iant]

thee intrisical areas I work at have absolutely no PLC gear inside that area.
Pneumatic Pressure reed switch
Nemur gear etc