Re: [foxboro] FBM 01 Connection issues
- From: "Joseph M. Riccardi" <Joe@xxxxxxxxxxxxx>
- To: <foxboro@xxxxxxxxxxxxx>
- Date: Tue, 28 Sep 2010 09:59:33 -0400
Gonzalo,
The 4-wire designation refers to transmitter/analyzer side of the circuit
where 2 wires are for the 120/240 VAC typical power source (or in your case,
+24VCC?) and 2 wires are for the 4-20 MADC signal output. Since the Gas
analyzers are self-powered (separate 120/240 VAC power source, or in your
case, +24VCC?), you "cannot" connect to the FBM01 P terminal (P = power
source from the FBM). I am not sure what the issue is at this point because
as I reread your e-mail, it is connected correctly and working as it should
with the following connection:
+24VCC -------o------- to external power source (+24)
Signal -------o------- FBM01 (+)
DC Com -------o------- FBM01 (-) also attached to external power source (-)
Although I have no idea what +24VCC means...
I believe the FBM01 inputs are all isolated so connecting the FBM01 (-) to
external power source (-) should not be an issue.
What help/answers are you looking for at this point in time?
Joseph M. Riccardi
DCS Services - Industrial Process Control
Joe@xxxxxxxxxxxxx
"To give real service you must add something that cannot be bought or
measured with money; and that is sincerity and integrity." - Donald A. Adams
-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx] On
Behalf Of Gonzalo Díaz
Sent: Tuesday, September 28, 2010 9:35 AM
To: foxboro@xxxxxxxxxxxxx
Subject: Re: [foxboro] FBM 01 Connection issues
The thing is that it is not a 4-wire transmitter. I also saw in the past 4
wire transmitters of this kind but in this case the transmitter has only 3
wires, which is fairly common. In a PLC, there is no problem to connect this
kind of devices, because the "field" power source is the same as the PLC;
but in this case, the power source that I use to "wet" contacts and to power
devices (such as flowmeters) is not the same source that the FBM01 module
has; so I was kinda worried to "bind" the negatives of the field power
source and the module's power source...
PS: i'm also receiving this failure notice mails...
Gonzalo Diaz
-----Mensaje original-----
De: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx] En
nombre de Joseph M. Riccardi
Enviado el: Lunes, 27 de Septiembre de 2010 16:07
Para: foxboro@xxxxxxxxxxxxx
Asunto: Re: [foxboro] FBM 01 Connection issues
Gonzalo,
If it is a 4 wire transmitter, as most Gas analyzers are, you do not use the
P terminal. Simply connect the + to + and - to - terminals.
Joseph M. Riccardi
DCS Services - Industrial Process Control
Joe@xxxxxxxxxxxxx
"To give real service you must add something that cannot be bought or
measured with money; and that is sincerity and integrity." - Donald A. Adams
-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx] On
Behalf Of Gonzalo Díaz
Sent: Monday, September 27, 2010 9:12 AM
To: foxboro@xxxxxxxxxxxxx
Subject: [foxboro] FBM 01 Connection issues
Hello to you all, I have a problem trying to connect a 4-20 mA gas detector
to a FBM01 card.
Te gas detector has the following connection diagram (hope my drawings wont
be affected by mail systems):
o------- +24vcc
o------- Signal
o------- DC Common
As you may see, the sensor needs to be powered, and the "signal" comes as a
current source from the device, in a separate cable
In the other hand, the connection diagram for the FBM01 is as following:
o------- P
o------- (+)
o------- (-)
I thought that the following connection would work, so I connected the
device as following:
DEVICE SIDE / FBM01 SIDE
+24VCC -------o------- P
Signal -------o------- (+)
DC Com -------o------- (-)
But it didn't work. The way it DID work, was as following:
+24VCC -------o------- to external power source (+24)
Signal -------o------- FBM01 (+)
DC Com -------o------- FBM01 (-) also attached to external power source (-)
Hope you can understand it. I connected the DC Common signal of the device
to the FBM01 (-) and ALSO to the external power source (-) terminal.
I do know this should work (the current loop goes through the external power
source instead of the FBM01 module) but I also know that it is not correct
to "bind" two different "negatives" from different sources.
Any ideas? Why the first option didn't work? How did you managed to do this
on your systems??
Best regards!
Gonzalo Diaz
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This mailing list is neither sponsored nor endorsed by Invensys Process
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your own risks. Read http://www.thecassandraproject.org/disclaimer.html
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_______________________________________________________________________
This mailing list is neither sponsored nor endorsed by Invensys Process
Systems (formerly The Foxboro Company). Use the info you obtain here at
your own risks. Read http://www.thecassandraproject.org/disclaimer.html
foxboro mailing list: //www.freelists.org/list/foxboro
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