agonified

QUOTE(Mikkel @ Aug 8 2007, 06:44 AM) I just noticed this Mikkel thanks for pointing out. I feel so noob. However, I am pretty sure that problem is not flushing out the buffer cause at the end of the serial cable, there is another computer which is showing me hyperterminal right now. I can't respond in few milliseconds right? Thanks a lot though. It was such a big foolish design mistake...

Hi again everyone, I've got this adapter to connect a serial device to the computer. I set port in Labview so that it terminates reading when a terminating character is sent by the device. When I use onboard serial port, it works flawlessly but that USB to serial port(rs-232) adapter does not terminate even device sends a terminating character. I first configure port to accept terminating characer and wire the output 'VISA resource name' to the write&read VI. When I use onboard port, reading is terminated immediately after device sends a terminating character. But when I use USB to serial port, it waits 'timeout' milliseconds(set during configure serial port) and then terminates without an error even if device responds correctly. If the device is not connected, it waits 'timeout' milliseconds and terminates with 'VISA: (Hex 0xBFFF0015) Timeout expired before operation completed' error. What the heck is happening here guys? How can I correct this? Did it happed to you before? That would be great if you could look at the code attached. I will actually connect two devices but my motherboard has only one port. That's why I need that secondary port. One other solution might be converting onboard serial port to rs-485 protocol with a converter such as this one and connect devices with a single port for daisy-chain communication style which my devices already support. My question about that issue is will that converter work in the way I want? Does it really converts protocol to rs-485 or should I obtain a PCI rs-485 port? Any help is greatly appreciated, Hakan

QUOTE(crelf @ Aug 2 2007, 12:20 AM) Well, I wish I could buy you an ice cold bloddy beer... Cause you were right.. Cheers! :beer:

QUOTE(crelf @ Aug 1 2007, 09:14 PM) Yes it is. But it is not mentioned that whether it requires rs232 or rs485. So, knowing that only one device can respond at a time, is it still impossible to go with rs232? I don't want to buy new hardware...

QUOTE(rpursley @ Aug 1 2007, 08:52 PM) Then, why I can read messages sent from only one of the clients in my test environment?

QUOTE(crelf @ Aug 1 2007, 04:09 PM) Actually, they do not respond at the same time: they have network addresses so that users can use them on the same LINE. 'readvariable1' means 'only device which has network address 1 must respond, others keep slient'. So there is no reason for my computer to get confused because at a given time, there is only one device trying to talk to the PC. QUOTE(Doon @ Aug 1 2007, 05:05 PM) This may be a silly question, but did you check for an auxiliary COM port on your motherboard? Nope, already checked, no luck... I still don't understand why this setup does not work. Can someone clarify me before I go with other solutions? I will most probably go with second rs232 interface. Thanks everyone. Such a great community you are... :worship:

Hi everyone, I am using Labview to control two devices which must be controlled via rs232 protocol. Communication is so simple; connecting only Tx, Rx, and, ground pins is enough and sending string commands such as 'setvalue' and 'readvalue' makes controlling the device easily possible. My problem is, devices are upstairs and I want to use only one cable to connect both of them(BTW there is only one serial port on my pc). A single cable out of the com port is seperated into two with a 'Y' adapter near the devices. This is where the problem occurs. I can't get response from devices when I connect both of them. However, if I remove the cable between one of the devices and the 'Y' adapter, other works perfectly. I set up a testing environment at home with three computers such that at a given time, one was 'server' and other two were 'client's. I applied same wiring schema via com ports and the results were strange: both of the clients were able to get messages from server but server was only getting messages from one of the clients. I tried all possible combinations like exchaning server with client1 and client2. No luck... Same happened. Server computer was able to read messages sent by only one of the clients. Strange enough, in case of connecting my devices upstairs, I could not get response from any of them. I am not able to locate the source of the problem unfortunately. As far as I can imagine, it might be diffrence in the ground pins voltage levels of the three of the computers and/or devices. Can someone please explain me what's wrong with my wiring setup? And, if it is completely out of the abilities of the rs232 protocol, what are the other cheap solutions? FYI, my devices can also use rs485 protocol to communicate. Thanks in advance.