Best Connection of Loadcell monitor to PLC

[GERRY JERESANO 0]

I'm tired of using 4-20 connection of load cell monitor to analog input. I'm thinking to switch to RS 485 or Rs 232 or Eternet but i have no idea how to configure the plc to connect to Load cell monitor.

Then what command i can use to the programmer to be able to use it.' ( 4-20 connection is not accurate because sometimes data may not be the same to the load cell out.) I use the analogue converter see the attached image. I get that here in mRPLC Forum.

Guys help me please.

Thank you.

[IO_Rack 181]

I agree you be more accurate using communications. To use serial communications you'll need to look at the TXD and RXD instructions. For Ethernet I would suggest using the Ethernet/IP protocol. Be sure that each Ethernet port you choose will support the Ethernet/IP protocol.

[GERRY JERESANO 0]

Thank you IO_Rack. But i need more study to do that. If in case i use Ethernet/IP com.  What command or data should i use?

Thank you in advance. 

[IO_Rack 181]

First you must make sure your hardware will support the Ethernet/IP protocol. The PLC will be the master or commonly referred to as a Scanner. Some smaller Omron PLCs with Ethernet ports will not support being a Scanner. What model PLC are you using?

The scale you use must also support the Ethernet/IP protocol. The scale documentation will outline the data exchange and supply you with an EDS file. The EDS file will be imported into Omron's Network Configurator software then downloaded to the PLC so that the PLC can know what data to exchange. No command will be necessary. The data will be exchanged cyclically to the memory you choose in Network Configurator.

Sounds easy, right? Sometimes it is and sometimes it is not. Let us know what hardware you are using. Maybe some forum members can suggest hardware they have had success with.

 

[GERRY JERESANO 0]

Thank you IO_Rack. I'm using Cj2m_Cpu31 and Pt210 weighing indicator  with ethernet port. 

[IO_Rack 181]

I took a quick look at the PT brochure. It appears your options are:

1) RS232C - In this case you would use the RXD instruction in the CJ2.

2) Ethernet (Modbus TCP) - The PT is not capable of Ethernet/IP but you may be able to use Modbus. I don't know how.

My suggestion is to use RS232C. I would set the scale to 'Streaming' then read the stream of data with the RXD instruction. There are examples here in the downloads section. Set your weighing indicator to 'Streaming' then test it with your PC and some terminal program like Realterm. Once you know it is outputting data, then you can connect it to the CJ2 serial port and begin programming RXD instruction.

[LD_M 2]

There is a third party supplier of Omron, Unipulse, which supplies a weighing unit card.  This weighing card is modular type, and can connect easily with CJ plc's.  The model of the weighing unit card is F159, which you can also select when you add a module in the plc i/o table, under general purpose analog i/o.  

If you access the website of the weighing card supplier, you can also download the ready made cx-one program, which you can tailor-fit to your application. Also, you need to download the eds file ( called cps ) for this module.

There was a post before regarding the usage of this weighing unit, but comment / reply was limited.  

Cheers.

 

[GERRY JERESANO 0]

@LD_M

Thanks for the great info.