Dear Expert,

   I have 8AI (6ES71346GF000AA1) module with base unit (6ES71936BP000BA0)without AUX terminal. How do i connect 4wire transmitter with 230v supply in this module.

Thanks in advance

 Hi CaOd,

    Thanks for your replay,

If i give 230v to the transmitter from external supply ( not from the ET200sp), is there any possibility to connect return 4-20mA  signal in Ai card.

CaOd

Hello,

you can't connect a 230 V AC transmitter to the 

ET 200SP Analog input module

AI 8xI 2-/4-wire BA (6ES7134-6GF00-0AA1)

You need a transmitter with 24 V DC.

Otherwise do you need a transducer to connect your transmitter to the PLC.

regards
CaOd

Hello,

and what says documenttaion from your transmitter? Generally inside documenttaion are examples and diagrams how wire and connect transmitter to devices, also some specification of output is probably included.

Here's how I interpret the 2 wire connections on page 11 pdf, used to power a passive loop powered field device.

L+ is filtered at station 7, split to terminal P1, fused by a 3A fuse, the current limited at station 4, which the supplies power to terminals 9-16 labeled Uv.

Uv (terminal 9 in the example diagram) feeds DC power to the (+) side of a 2-wire transmitter.  The (-) side of the 2 wire transmitter connects to an In+ terminal, terminal 1 in the example (very conventional passive, 2-wire connections).  The current loop signal creates an IR drop across the unlabeled rectangle, presumably a dropping resistor, creating a parallel voltage signal for station 3, the A/D.  The return for the current is to P2 or the M ground.

The 4-wire diagram, page 12 pdf, is very confusing to me:

A line powered device has a high probability of having an active, powered 4-20mA output.   As such, it could isolated or not isolated (from the ground at the field device).

Some line powered devices offer a passive, loop powered output requiring an external DC power source (like the Siemens LUT400 ultrasonic controller), but specifically state that in their documentation.  A passive loop powered output would be wired according to the 2 wire connections described above, (+) to a Uv terminal, (-) to an Im+ terminal.

The 4-wire connections are really confusing.

The Uv terminals are DC power, not needed for an active output.

A note says the P1, P2 and Aux are 'internal self-assembling voltage buses" but why would a voltage bus be shorted to ground across station 4, the filter connection?  I can't make sense out of that.  P2 is directly connected to ground, too.   I don't understand the description.

Since M connects directly to terminal 10A which is connected to all other nA terminals, I have to assume nA terminals are grounded.

The example of the 4-wire transmitter shows two nA (terminals 6A, 8A) ground connections, one to a (-) terminal on the field device, the other unlabeled.

A Uv power source from terminal 10 connects to the (+) terminal on the 4 wire device.

An unlabeled 4-wire device terminal connects to In+, one of the current signal inputs.

In both 2 wire and 4 wire examples the return side of the IR dropping resistor are internal,

I would think that the (+) output of a field device active output could connect to an In+ terminal, so current flows through the dropping resistor and returns to a P2 ground point.  The field device's (-) connection would connect to ground through station 7 to the P2 point.  But if that's what the example is trying to show, I can't explain it.  There would be no Uv connection at all for an active output, because the active output is powered by the 4 wire device.

I'd say you need to read the 4 wire device manual to see whether the output is active (powered by the field device power) or passive, powered by an external DC power supply and then pick whichever wiring suits the device.

If the output is active and not isolated, you risk a ground that can add or subtract current from the current loop, creating an offset, a saturated output (offscale upscale or downscale) or a burned out AI or AO depending the magnitude of the ground potential difference.  That issue is typically resolved with a loop isolator, which breaks the grounds on either side so potential differences can not generate a current through the loop.

manual at this link:
https://support.industry.siemens.com/cs/ww/en/view/109475183 

Hello,

A few years later, let me make my contribution to this post so it may help someone.

I just tested different configurations in 2-wire and 4-wire with this module on a base unit without AUX bus bar, and it works.

1st : 2-wire, as shown in the manual. The U terminal provides the power to a passive sensor, the current comes back to the module through the I terminal. Configuration of the channel in the software as a 2-wire device.

2nd : same wiring configuration, but in the software, the input is set as a 4-wire signal. Nothing changes, the signal as interpreted by the module remains correct.

3rd : 4-wire with external power supply. I only wire the signal loop as follows : ground (M) -> active device (signal part) -> I terminal. It works perfectly.

As most of our 4-wire devices use 230V power supply, I didn't test 4-wire with power supplied by the module, however I see no reason why this wouldn't work by wiring a loop U terminal -> device (power part) -> ground (M).

Anyway, for a 4-wire device, if the device is set as passive, it should be considered as a 2-wire device regarding the signal and wired accordingly (otherwise there would be no current).

Have a good day everybody !