Hi, I'm trying to create a testing environment for temperature and humidity with Labview. My problem is that I can't communicate with the device which controls parameters. My equipment is the following: -West 4400 1/4 Din Profile controller -USB485ui serial adapter from Amplicon Communication protocol is Modbus RTU.

I tried to communicate and to send modbus command with Hyperterminal, Labview VIs (Looppack or Modbus pack) and others softwares but I can't get any response from the device. Visa detects it on COM port. Revere Stereo 33 Camera Instruction Manual. It seems that the device is connected but I must send bad commands to it. Is there any simple mean to chek that a modbus device is communicating? I'm just a beginner in modbus protocol so if someone could give me any help or advice, it would be great.

Hi, I am now able to fully control the West device, but I am having some trouble when I try to add others slave devices. I am trying to control the environmental chamber and to read data from sensors simultaneously. The two devices are communicating with Modbus RTU on the same serial RS485 port. I found that it is a common problem when you are connecting two slave devices on the same serial port. Timeout Error are occurring and it looks like the Labview serial function can't read and write data on both devices at the same time. It works well in highlight or step mode but not in continuous mode.

National Instruments advertises a free native Modbus TCP/IP library that has been used successfully with our Modbus TCP compatable devices. Some of its features include Works with standard serial and Ethernet ports Facilitates Modbus TCP/IP and serial. T7 T7-Pro PLC RTU Modbus TCP LabVIEW Example. This file contains information about OMEGA Platinum ® Controllers LABVIEW Driver and DLL Driver for.NET. The file OmegaPlatinumModbusDriver.llb contains necessary library files; Platinum Serial Modbus (USB Virtual Comport and RS232, RS485) includes the following VIs. Example LABVIEW applications.

Is it possible to connect two modbus devices on the same com port and to communicate with both on Labview? Modbus/RTU on RS-485 can definitely be used with multiple devices. This is in fact usually the reason why RS-485 is used at all (instead of RS-232). You can have up to 32 nodes on standard RS-485, and that limitation is due to the electrical characteristics of the chips and cabling. There is however no mechanism built into RS-485 to allow multiple devices to communicate at the same time without stepping on each other's toes. If two devices try to communicate (reply) at the same time they will interfere with each other. If you were using Ethernet TCP/IP it would take care of those coordination issues for you.