AI to AO Direct Hardwire
AI to AO Direct Hardwire
(OP)
An analog output signal generated by SIEMENS DCS needs to transfer a package unit PLC (also by SIEMENS) through an analog input channel as depicted below. Question is, will work or an isolator will be need?





RE: AI to AO Direct Hardwire
> How far apart are they and are they on the same power distribution?
TTFN (ta ta for now)
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RE: AI to AO Direct Hardwire
Since you have both a PC system and a DCS, I will assume that each system with have it's own 24Vdc power supply. Unless either the DCS OP or the PLC IP card is isolated, I would install an isolator between the two devices.
GG
"I have not failed. I've just found 10,000 ways that won't work." Thomas Alva Edison (1847-1931)
RE: AI to AO Direct Hardwire
Because both cards generat loop powered signals.
They are both in a control room.
RE: AI to AO Direct Hardwire
It is used to debug the control algorithms on the PLC, PC plays the role of a plant.
RE: AI to AO Direct Hardwire
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm
RE: AI to AO Direct Hardwire
RE: AI to AO Direct Hardwire
RE: AI to AO Direct Hardwire
RE: AI to AO Direct Hardwire
I know its off topic, but it seems unusual that this arrangement would still be required, unless this is an existing plant that doesn't have a higher level communications ability.
EDMS Australia
RE: AI to AO Direct Hardwire
If the process needs whatever's on HART and you use isolators, then you need HART transparent isolators. Most isolators strip off the HART and just pass the 4-20mA through, so the output side of the isolator has no HART signal. In fact, some isolators have a low pass filter on the input side that will strip off HART, too. HART enabled/transparent isolators are clearly marked and priced accordingly.
2. If the boxes are in the same building, you might get away without isolators. Can you connect the points and try and see whether the common mode/ground loops offset or drive the signals off scale? No offset, no problem.
3. Both racks are Siemens. Why not Profibus?
RE: AI to AO Direct Hardwire
Yes, it's really annoying, especially if such equipment is used for training purposes ... Serious guys offer a cheap kit DAQ- Motherboard + known modules and microcircuits. In their boring video lessons and in complete silence, they show examples of the use of this junk.