Know a good loadcell transmitter ?

Hi.

I am looking for a suitable loadcell transmitter.
It shall be for connecting 3 or 4 load cells, and it shall give one output signal of 4-20 mA.
Loadcells are the classical resistive fullbridge type.

I wonder if there are types with a dedicated input for each loadcell.
I want to awoid using an external summing box. To my experience, the transmitters with only one input for several load cells are a pain to troubleshoot.

I also prefer it if the setup is done via a menu in a small display. Dipswitches and potentiometers are no-no.

At the moment I am using a digital loadcell+transmitter combination.
It has a dedicated input per loadcell, if the loadcell is OK then there is a green LED that lights up.
Also, there is a small display and a few buttons with which to setup and troubleshoot everything.
It is so much more comfortable to use than the older type transmitters. But the problem is that it is a propriatery solution for this particular manufacturers loadcells.

Thanks for anyone who can point me to such a thing.

Check hardy instrment , mettller toledo or fairbanks
there is a company called precision instrument that i had contact with but i lost it. they have differnt types for analogue or digital transmitters (modbus , profibus,....)

http://www.hardyinst.com/products/index.php?id=56


Talking about weiging , did you try simens siwarex modules ?

What is special about the load cells ? Are you saying you could not use another load cell from another manufacturer with the same sensitivity and connect it to your existing system.

Hi Amr Hassan.

Well, plowing through all these manufacturers websites is what I hoped I could avoid by asking here (yes I am lazy, but when so many ask questions like that, why cant I ?).

I considered Siwarex, but I find that a locally mounted transmitter with a small display is a godsend for commisioning and troubleshooting.

edit: The transmitter that you linked to is exactly the type I want to avoid !

Hi SimonGoldsworthy

The loadcells I use now are special. The loadcells and the transmitter communicate with each other via a propriatery bus.
They are good, but I want to see if I can use a "general purpose" transmitter so that I am not tied to a particular loadcell manufacturer.

I have tried many of the old style transmitters with summing boxes, dip switches and potentiometers, and NO indication of anything if something is wrong. There must be something more modern out there.

Hi JasperMP,

Which PLC are you using?

If you are using an S7-300 or S7-400 from Siemens, you can use the Siwarex modules also from Siemens. They work with any type of load cells, and they are configured with a special software (no pots and no dip switches).

Hi nonuke.

Actually I do use S7, but I have disregarded Siwarex because it more or less means that I have to pull all cables back to the PLC in the control panel. This I want to avoid.
A local ET200S box would also be possible, but is ruled out for a number of reasons.

The type we use now is great because one man can easily and quickly commision or troubleshoot everything. Placing the transmitter far away from the loadcells means goodbye to that.

Do you have experience with Siwarex ?
Is it absolutely required to use the special software to set them up ?
Cant they be inserted in an ET200S station and then be setup from the program ?
I checked the ET200S modules Siwarex CS and CF.
It looked to me like the CS modules are very complicated whereas the CF modules are more simple. If I use Siwarex CF, do I need any special software ?

OK Jesper, I know your English is better than mine BUT state exactly what you need. I am confused...again.

Sometimes I confuse myself too.

I want a loadcell transmitter to use with "standard" resistive fullbridge loadcells.

3 or 4 loadcells should be connectable with a dedicated input for each loadcell. Not just one input for several loadcells.

Output should be 4-20 mA.

And I want to setup the transmitter with a display. Not dipswitches and potentiometers.
And if there is clear and meaningfull error messages like "loadcell 2 out of range", "broken wire to loadcell 1" or "loadcells off balance" it would be brilliant.

I want to install the transmitter locally at the scale.

Hi Jasper,

We used SiwarexU 7MH4601-1AA01 a few times, and they work great and are easy to setup. They can connect localy to an IM153-1 so you only need a profibus cable to the PLC. you can even install in the same panel a TP170, and you will have a controller next to the cells.Siemens even has an example of a TP170 working as a load cell controller (all pusbuttons and displays etc.).
They also have a version with two controllers in the same module 7MH4601-1BA01 .
Yes they need a software for configuration and callibration: 7MH4683-3AA63.

Hi nonuke

I am afraid of the need of using a special software package for setting up the system.
For most of my customers this is out of the question.
Is it possible to setup Siwarex via the S7 program and thus avoid the software ?

Do you have any experience with the ET200S CF modules ?
They seem to be the simpler version, and I therefore hope that they just work like any normal input in the S7 system with no need for special setup. I am very confused about Siwarex. The manuals are not so helpful.

Hi Jesper,
I never used the ET200S CF module.
You configure the Siwarex in S7 with the GSD file as you do with any profibus module.
The special software package is for you to configure the siwarex module (type of cells,max weight etc), and you only need it to start up the system. You can use the same software in future projects. you don't give the software to your client and he doesn't need it. This software is like the software used to setup frq. drives etc.

nonuke said:

The special software package is for you to configure the siwarex module (type of cells,max weight etc), and you only need it to start up the system. You can use the same software in future projects.

Click to expand...

What happens if a module must be replaced onsite ? If the settings are stored on the module, you have to go online with it.
Is it not possible to store the settings in the S7 program and then configure it via the program ?

I have used the time between your posts to scrutinise the Siwarex CF manual, and it looks like it is just like I want it. No setup software, just an analog input value that I can use in the program.

Despite that I consider using Siwarex, I still prefer to have a dedicated transmitter like I wrote before.
The ET200S Siwarex CF solution is a bit expensive, and I would really like to have a display right next to the load cells, not 20-30 m away.

Jesper,

I havent tried their 4 channel unit but I do use the Cooper DFI Infinity on all my load cell applications. Here is a link to a 4 channel that they offer.

http://cooperinst.thomasnet.com/item/digital-force-indicators/dfi-3900-4-channel-indicator/dfi-3900?&forward=1

Bob

Thanks Bob.

It is exactly what I am after. You dont have an approximate price on that thing ?

I have begun thrawling the net, and I have found one good candidate myself:
http://www.vetek.net/shop/arts/detail.aspx?artID=1335
DIN-rail mountable, and at 578 Euro it is within the price bracket I can afford.

JesperMP said:

Thanks Bob.

It is exactly what I am after. You dont have an approximate price on that thing ?

I have begun thrawling the net, and I have found one good candidate myself:
http://www.vetek.net/shop/arts/detail.aspx?artID=1335
DIN-rail mountable, and at 578 Euro it is within the price bracket I can afford.

Click to expand...

Not sure the price on this one. I get the single channel Infinity model for under $400.

Bob