Re: [foxboro] FBM 01 Connection issues
- From: Terry Doucet <doucet427@xxxxxxxxxxx>
- To: <foxboro@xxxxxxxxxxxxx>
- Date: Tue, 28 Sep 2010 10:49:54 -0400
The English term "direct current - (DC)" translates to French as "courant
continue" and to Spanish as "corriente continua" so one of those is the likely
meaning of "CC".
The FBM01 and the FBM201 are totally isolated so it is almost impossible to
damage them unless one connects 120 V or 250V directly onto ther terminals.
P is a positive voltage on the FBM that is totally isolated from ground and
other FBM channels. As Dale stated, it does not have much power being limited
to about 30 mA. You can connect the negative to the negative of the FBM, again
because of the total isolation. If your external 24 V CC powers more than one
transmitter into many FBM01's you can connect the common negative of the power
supply to the negative of each FBM channel without any damage. Although you
have not shown the detail, you may need to give some security to the external
24V (redundant power supplies, diode protected) and a fuse with enough capacity
to drive your device and the 20 mA loop. This way a slip of a screw driver will
blow a fuse and not the whole power supply.
Terry
> From: Gonzalo.Diaz@xxxxxxxxxxxxxxxxx
> To: foxboro@xxxxxxxxxxxxx
> Date: Tue, 28 Sep 2010 11:12:09 -0300
> Subject: Re: [foxboro] FBM 01 Connection issues
>
> Joseph, thanks for your time answering this. The answer that I was looking
> for was if connecting both "negatives" could yield to any issue on the FBM01
> or not. The gas detector is powered with 24 VCC. So for the device, the
> +24VCC stands for "positive".
>
> I thought at first that since the "P" has positive voltage from the FBM board
> (loop powered devices are connected to this terminal and "+") it could "feed"
> the device, but it didn't work. It is very possible that the FBM has no
> sufficient power for the device, as Dale stands. So I connected the way I
> described it and worked, but I hesitate a lot on putting together the
> negatives that are from different sources. But that's it, it seemed quite odd
> at first glance.
>
> Best regards,
>
>
> Gonzalo Diaz
>
>
> -----Mensaje original-----
> De: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx] En
> nombre de Joseph M. Riccardi
> Enviado el: Martes, 28 de Septiembre de 2010 11:00
> Para: foxboro@xxxxxxxxxxxxx
> Asunto: Re: [foxboro] FBM 01 Connection issues
>
> 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
>
>
_______________________________________________________________________
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
to subscribe: mailto:foxboro-request@xxxxxxxxxxxxx?subject=join
to unsubscribe: mailto:foxboro-request@xxxxxxxxxxxxx?subject=leave
Other related posts:
