Hi
Has anyone used the Sierra Tm100 Thermal Mass FT (4-wire)? I have one query regarding the 4-20mA connection. I followed the product manual for 4-20 mA termination, but still the transmitter is unable to transmit the 4-20 mA signal in SCADA (the loop was clear; no issue with the cable). From the attached drawing, is the manufacturer recommending using a 250-ohm resistor? But why does my control system have I/O (Siemens S-1500, AI Siemens ET200SP series) already loaded with resistance? I haven't seen it for Siemens Corilios FT, Yokogawa, Honeywell, or ABB. Is it recommended?

 

Does SCADA supply loop power? Or does SCADA want and expect a powered 4-20mA signal?

How did you wire the Sierra 4-20mA output?

The top diagram is for a passive, loop-powered 4-20mA (where SCADA might provide the DC power to power the loop).

The bottom diagram is where the DC power powering the Sierra also powers the 4-20mA, similar to an active, powered output.

 

Does SCADA supply loop power? Or does SCADA want and expect a powered 4-20mA signal?

How did you wire the Sierra 4-20mA output?

The top diagram is for a passive, loop-powered 4-20mA (where SCADA might provide the DC power to power the loop).

The bottom diagram is where the DC power powering the Sierra also powers the 4-20mA, similar to an active, powered output.

View attachment 5662

View attachment 5663

Initally i have followed the first image later i have tried the sencond image to find any changes.
Yes, The SCADA wants and expect a powered 4-20mA signal.

 

If you use HART, then HART needs 250 Ohms of loop resistance to function properly.

In either case, the 4-20mA circuit needs to be powered. Either from an external (24V) DC loop power supply or from the DC power supply that drives the thermal dispersion measurement.

If the SCADA expects an active signal, then SCADA is not supplying loop power. Where is your DC power coming from?

 

If you use HART, then HART needs 250 Ohms of loop resistance to function properly.

In either case, the 4-20mA circuit needs to be powered. Either from an external (24V) DC loop power supply or from the DC power supply that drives the thermal dispersion measurement.

If the SCADA expects an active signal, then SCADA is not supplying loop power. Where is your DC power coming from?

DC power is comming from RIO panel. I have connected via jumper + ve 4-20mA to +ve24vdc still no value is displayed in SCADA.

 

You'll have to sketch out exactly what connects to what with links to the hardware manuals and post it here.

 

Dear Avinash,

Please check whether you’ve already configured the ET200SP in Hardware Config in TIA Portal. On the Hardware Config page there are settings for the white and grey potential terminals that are worth checking.

Hope that helps.