Hi,

I am using Siemens SM332 AO card giving 4-20mA to a 3rd party Siemens SM331 AI card. When I try to do a direct connection i get maximum values. What should i do in order to provide 4-20mA from my AO card to the AI card? I have two cases:

1] 4-20mA from my AO to a AI card that is configured as 2-wire.

2] 4-20mA from my AO to a AI card that is configured as 4-wire.

Appreciate someone could give me some idea.
Thanks in advance.

with regards,
snowball

 

Hi,

place a suitable isolator b/w ao & ai card and see. i hope this will work because it may be happened due to channel loading.

regards
ram

 

Hello,

The simple answer is to use a signal isolator. However if you study the wiring drawing you may have other options.

If the output module supplies loop power you will not be able to connect to a 2 wire input because that also supplies power. If the power supplies are referenced to different points you may have difficulty without an isolator (possible ground loop).

Signal isolators come in all different Input / Output configurations so you need to be very careful selecting the right one.

If you post you module model numbers someone more familiar may be able to help further.

Regards,
Roy

 

Normally , AO cards are source signal [4-20 madc] & hence when you connect it to AI card of the any other system. You have to consider or wire AI module only as 4-20 madc, 4 wire system.

You need to check the wiring of Siemens AI module there is separate PS [24 VDC] connection given to the module itself, either for powering module or transmitter power supply or both.

Check the manual properly & connect it accordingly, earlier we used to testing like this for panel mounted instruments. Also important is check the internal connection of module. is it 0 - 5vdc or 1-5 vdc[4-20 madc 250 ohms R]? If it is 0 - 5 vdc, than what you require by default ISOLATORS for connection.

Our reply is very general conceptual, apply it with Siemens hardware using wiring manual of Siemens.

Jari
Iconcnl [at] vsnl.net

 

Hi guys,

Thank you very much for the suggestions
My AO card model is 6ES7-332-5HF00-0AB0
and the AI card model is 6ES7-331-7KF02-0AB0.

Any other options if don't use an isolator?

Thanks!

with regards,
snowball

 

hi,

don't worry u don't have any concept 4 wire and 2 wire at module end. if u want to test the AI module fron AO module, then just connect AO signal cable to AI module signal cable and force count to AO from program. (u can not force it through vat table) but u can see the input in vat table for AI module. so don't worry go on
in both the cases...