No communication on laptop


Thread Starter


I have Quantum PLC with 486 controller communicating to PC from Modbus com1 to PC com1 running ProWorx NxT software, from Modbus com2 thru RTU to Siemens drives, and also to PC on com2 running Wonderware software. The problem I have when I try to use laptop, which has only one com port, I have no communication, the OS and software are same on laptop and desktop.

Any help is apprecitiated.

You are substituting the laptop for the former PC? or attempting to run in parallel?

Windows serial ports got a bad report card in kindergarden:
does not share with others
does not play well with others

That's why your one PC has two COM ports, one for ProWorx, the other for Wonderware.

Your laptop should work with one or the other app. But you'll have to configure the COM port somewhere in the software - baud rate and all that.

If you need a second serial port for the other app, you'll probably have to use something like a USB to RS-232 adapter whose driver creates a virtual COM port used by the application. That COM port, too, would have to be configured in the software.

On rare occasions, one finds a faulty, dysfunctional serial port, but a test with a null modem cable between two PCs, each running hyperterminal (in the accessories folder) will test the serial port.

To add a another COM port to your labtop, you can either:

1. Use a USB-RS232 converter (less reliable)
2. Use a PCMCIA-RS232 converter (more reliable/recommended)