Serial Communication with rs232/485 and rj45

programmingrs232rs485

I am working a project where I want to connect and control, using Labview,

  • TDK-Lambda Power Supply
  • Process Vacuum Controller Ion Gauge (MODBUS interface)

They both have rs232/rs485 capabilities, just depends on a switch on the back of the terminal and both connections are with a rj45 jack (I will attach relevant manual). And connect via a RJ45 cable, and I want to connect it to a computer.

Now, I've set up a .vi that should be able to connect to, or at least discover, the devices but to no avail. It might be because I am using a regular Cat5E Patch/Ethernet Cable and it therefore not the right pinout. I've tried to read some post and/or white papers about the subject, but these devices are specific and have different pinouts.

So my question is, how to I go about using an rj45 cable for serial communications? Can I simply connecting a cat5 cable to my laptops ethernet port and to one of the devices serial rj45 jack? Or am I missing something major?

This is my first attempt at anything like this, but I have used Labview to connect to serial DB9 to usb adapters and able to communicate.

Here is a link to the PVC Ion Gauge Manual
And the TDK-Lambda Power Supply

I know I am asking for a lot of help here, but I am super lost and any help is much appreciated.

Best Answer

You are missing something major. You CANNOT connect a serial connection to an ethernet port and get anything useful out of it.

You will need an adapter from RJ45 to an RS232 conector (usually Sub D9) or to an RS485 connector (Not sure what this looks like.) You will then need the appropriate interface on your PC - that would be a serial port for the RS232, or a special interface for the RS485. Both of these can be had as external units that connect to your PC via USB.

You will then need a VI for Labview that can use the adapter. RS232 should be standard, I don't know about RS485. You can probably purchase an adapter from National that will include the correct VI and or drivers.

Both manuals include information on how to wire the RJ45 to a serial cable. You will have to either build them yourself or try to order them from the equipment manufacturer.