seeking Foundation Fieldbus guru - troubleshoot bench test FF field transmitters

My attempt to communicate with Foundation Fieldbus transmitters with Pactware and a new, out-of-the-box Softing FF modem are a disaster - failure communicate with the field device.

Pactware consistently issues Error 4 and the connection icon never goes green.

A Relcom FF certified DC power supply is used to power the field transmitter. Cables are shielded twisted pair (although in this conference room bench top situation, there is no hard earth ground connection because the F11 is not on DIN rail because the DIN rail would float, too; it's all on the table top. I just checked and the F11 body is plastic and its DIN rail clip is plastic, so the F11 apparently does not earth ground, even though the shield connections are made on the terminal blocks on the F11.


The modem is a Softing Mobilink modem that has successfully had a Foundation Fieldbus license generated and loaded onto the modem. The Softing Manager software confirms the presence of FF license.

The Relcom F11 has termination built in on its end. Those I have spoken to say the for bench testing with 18" (0.5m) of cable, termination on the field transmitter is not necessary, but I have nonetheless experimented with a homemade terminator, 100 Ohms in series with 1uF across the transmitter (+) and (-) terminals. There has been no connection in combinations of

- single FF transmitter, terminator or terminator
- two FF transmitters, terminator or terminator


The MobiLink modem's leads are connected across the transmitter's (+) and (-) terminals, along with the DC power supply.

The transmitter's local integral digital display lights up so the transmitter is powered OK.

The MobiLink FF LED only flashes once every 9 seconds. No clue as to why.

Windows Device Manager 'sees' the Softing Modem.

Pactware reports the Softing modem's serial number, which infers that Pactware can 'see' and talk to the modem.

But Pactware's connection icon never goes green, like it should and like it does when a USB/HART modem is used with the same laptop/Pactware software.

Softing's US tech support is stymied. The Germans are at home for the evening.

Anyone have a clue?

Novice with FF, but don't you need a 100 ohm resistors at each end?

100 ohms across the transmitter (+) and (-) will trip the power supply crowbar overload protection because FF transmitters do not regulate the loop current like a 4-20mA does. The 100 ohm resistor draws more than the transmitter and trips the overload.


FF termination is 100 ohms in series with 1uF.

Any networked communications protocol need the following to work:
Media is installed correctly and no bad workmanship on install
Media terminations are the correct value and installed on each end,
Scanner master is at same baud rate as devices or are all devices set to an auto-negotiate baud rate.
Is there a way to see the media on network without configuring the scanner master? Most media devices when installed correctly will show up on network display. Example: Devicenet scanner and devices will show up on RSlinx if the media is installed correctly.

Are you sure you have the latest firmware version flashed for mobiLink (1.30)? As you can see from my environment, I get this to work. I am using M&M Systems container. I will install PACTWARE if you would like me to try something closer to your environment. Below I show the Windows screen grab and the actual picture of my setup. When I took the picture the FIELDBUS LED was flashing at about one Hertz.

And the pict...

I can get PACTware to detect the Cerabar device with the show live list command...

danw, It is very late here. I will check this post tomorrow in case you need more help.

I’m not ignoring you. Thanks for all your efforts.

I tried the HART side of the Mobilink modem and it connects OK. But Pactware refuses to load the Sidmens DTM, which makes me suspicious of the laptop/Pactware, not the hardware. I’m installing Pactware and the Mobilink drivers on a 2nd laptop. I’ll keep you posted.

Did you confirm the live list command in FF? Just to confirm that you do not have a media problem. Live list should work even without the DTM.

danw said:

But Pactware refuses to load the Sidmens DTM, which makes me suspicious of the laptop/Pactware, not the hardware. I’m installing Pactware and the Mobilink drivers on a 2nd laptop. I’ll keep you posted.

Click to expand...

Do you mean that when you try to update PACTware's DTM catalogue?
I would recommend that you close PACTware and the Softing tool (which is a customized DTM container) when you install the Siemens DTM. If anything DTM related is running, the installation may not succeed.
Also, you may want to try the M-M System's evaluation FDT/DTM container, in case there is an issue with PACTware and the Siemens DTMs:
https://www.mm-software.com/en/download
Finally, are those Siemens DTMs licensed software? Or is it possible to download them? if so, I can see if after downloading them to my PC, my PACTware and M-M System FDT/DTM containers can update the Siemens DTMs in their respective DTM catalogues.

I hope you can do some meaningful progress today. I have my FF stuff at home, so I can set it up quickly tonight if I need to test something to help you. I have the E&H Cerabar and a Yokogawa pressure transducer.

AlfredoQuintero, I salute you. A true engineer, with two transducers set up on his dining room table and a big ol heap of wiring, eager to help a comrade in distress.

(I have a full duplex Trio data radio base station on mine currently).

The above is also possibly why I'm not married.

Saffa said:

AlfredoQuintero, I salute you. A true engineer, with two transducers set up on his dining room table and a big ol heap of wiring, eager to help a comrade in distress.

(I have a full duplex Trio data radio base station on mine currently).

The above is also possibly why I'm not married.

Click to expand...

We're all brothers in arms. I have got so much help from this forum.
In my case I have managed to stay married for 22 years, in spite of these instruments on my messy heap of wiring at home.

AlfredoQuintero said:

We're all brothers in arms. I have got so much help from this forum.
In my case I have managed to stay married for 22 years, in spite of these instruments on my messy heap of wiring at home.

Click to expand...

I am so impressed with your efforts to help - I, too, noticed the setup at home.

It turns out that Softing is sending a 2nd Mobilink modem for me to try.

The HART side works OK - communicates with a field transmitter, all the little connect icons turn green, just like expected.

But the FF side just does not connect.

I expect the replacement unit shortly. I'll report back when it arrives and I can plug it in.

danw said:

I am so impressed with your efforts to help - I, too, noticed the setup at home.

It turns out that Softing is sending a 2nd Mobilink modem for me to try.

The HART side works OK - communicates with a field transmitter, all the little connect icons turn green, just like expected.

But the FF side just does not connect.

I expect the replacement unit shortly. I'll report back when it arrives and I can plug it in.

Click to expand...

Good luck then. I cannot loan you my mobilink, but I do have two FFusbs one of which I could send you if you are in a real urgency. The FFusb uses the same Softing commDTM.