communication between pc and plc

[nsimbe 0]

one of the members on this forum provided a drawing that can be used for communication between SP20 omronplc and a pc. now my laptop do not have the normal pc serial port. is it possible to use the USB port along with the USB to RS232 cable and then proceed with the remaining connections. Edited 12 Jan 2006 by nsimbe

[gravitar 3]

Generally a USB-to-RS232 converter can be used in place of a dedicated hardware serial port, but there are exceptions. Since you're asking about an Omron application, your best bet is to post this question in the Omron forum.

[bluebyu 4]

Found by searching in the Omron section http://forums.mrplc.com/index.php?showtopic...6&hl=usb+serial

[nsimbe 0]

now on running the minilss software along with the CPU killer on my computer i get this message[ the system cannot access COM1 port requested by the application]. please advise on the way forward.

[banker 2]

Check your windows hardware profile and see if the USB device is installed as a comm port and also as comm. port 1 Banker

[PdL 71]

I can imagine the driver for the USB/RS232 converter can't be properly set from within a DOS application !?

[moosty 0]

Hi, Try to use the mode command on command prompt. This command writes all available ports on your computer. Plug in and out your USB converter and try the mode command. You may see which comm port has been added while USB converter has plugged in. Here is a sample output on my computer: Microsoft Windows XP [Version 5.1.2600] © Copyright 1985-2001 Microsoft Corp. D:\Documents and Settings\ar208291>mode Status for device LPT1: ----------------------- Printer output is not being rerouted. Status for device COM3: ----------------------- Baud: 1200 Parity: None Data Bits: 7 Stop Bits: 1 Timeout: OFF XON/XOFF: OFF CTS handshaking: OFF DSR handshaking: OFF DSR sensitivity: OFF DTR circuit: ON RTS circuit: ON Status for device COM4: ----------------------- Baud: 1200 Parity: None Data Bits: 7 Stop Bits: 1 Timeout: OFF XON/XOFF: OFF CTS handshaking: OFF DSR handshaking: OFF DSR sensitivity: OFF DTR circuit: ON RTS circuit: ON Status for device COM1: ----------------------- Baud: 1200 Parity: None Data Bits: 7 Stop Bits: 1 Timeout: OFF XON/XOFF: OFF CTS handshaking: OFF DSR handshaking: OFF DSR sensitivity: OFF DTR circuit: ON RTS circuit: ON Status for device CON: ---------------------- Lines: 3000 Columns: 1000 Keyboard rate: 31 Keyboard delay: 1 Code page: 857 D:\Documents and Settings\ar208291>

[nsimbe 0]

when i try the mode command the display is similar to yours except STATUS FOR DEVICE COM 4 AND COM 1 are not displayed.secondly the status for device COM 3 on DTR circuit=OFF and RTS circuit=OFF. please advise on how to proceed from here.

[moosty 0]

Hi, Mode command only shows the available ports on your system. If any software opens one of the comm ports, you can not see the port. Did you try to plug in the USB converter, try mode command then plug out converter and try mode command again. If you see any differences, it means that your USB converter is visible from DOS. Also, you can look to device manager to see all installed ports on your system. to do this, right click "My Computer" icon on your computer, Click "Hardware" tab, then click "Device Manager" button. Click the "+" sign near the "Ports (Com&LPT) branch. You can see all ports installed on your system. I have attached a zip file including two jpg files. System see my USB converter as COM37, it is possible to change its name to COM1, however it is impossible in my PC because I have already COM1 port. May be you can change USB converters name to COM1. Hope this helps. Ports.zip

[nsimbe 0]

now the system can see the USB converter as COM5. so how do i change its name to COM1. otherwise it seems am on the right track to sort out this problem.

[PdL 71]

Go to control panel > system > device manager. Find the port you want to change at Ports (COM & LPT). Open to acces the properties, go to Port settings > advanced. Change the port number in the drop down box below. You might need to restart your system in order for the changes to take effect.

[BobB 58]

You may have to change an existing com 1 port to another number first.

[PdL 71]

Good call Bob, that's probably necessary.

[tarik 0]

My previous notebook does not have com port also I was using USB to RS232 converter. It was working with no problems.