PortServer TS16 Periodic loss of serial data

I’ve been handed a Portserver TS16 to evaluate. The Part No is 50000854-01B.

I’m using the RealPort virtual serial port drivers to try to talk to a serial device from a PC through the portserver over TCPIP - normal profile.

So far I beleive i have both the PC end and Portserver end set up OK. It’s not entireley working for me yet. The PC application polls the board at the other end using a 3 byte string. The board on the other side of Portserver should reply within a second with 73 bytes. Sometimes the receive routine times out. It will report having received half of the expected 73 bytes and then time out.

Then it will do four or five successful transactions, and then receive a half packet again.

I found that if i reboot the portserver, the transactions are fine and fluid for the first 60 seconds or so and then the odd half packet dropouts start occuring again. To be clear, it appears that transmissions from the PC are being translated through the portserver to my serial board but the 73 bytes that the serial board replies to the PC with are not entirely making it through.

I’m not sure what the PC application sets serial port receive timeouts to but we usually leave them longer than shorter. If the bytes are being translated but too late for our applications timeouts, is there a way to reduce the latency?

I have three different programs that are designed to perform the same transaction and all of them report short sheeted “packets” being returned from the end device. (yes the end device works fine on a normal serial port)

I updated the firmware to 82000684_V from H ( i think it was H) but that did not make a difference. The port server also doesn’t much like the ethernet cable being disconnected and then reconnected while the serial port is open. What settings reduce this effect? The disconnection/reconnection is probably going to happen in the field. I don’t want the serial port to screw up the application when this happens.

Any and all ideas welcome,

John Dowdell

I have discovered what the issue was. Thanks to those that read the post.

The PortServer did not like my DHCP server. I was using OpenDHCPServer and obviously the portserver was not receiving the expected DHCP info and so continually requested DHCP over and over again even though it had gotten an IP, subnet mask and gateway. I guess it wanted a few other DHCP fields that were either unpopulated or poulated with odd data/options.

The continual DHCP requests were upsetting the serial/IP connection.

I suspect it probably works fine with a decent DHCP server. For the moment I have set the PortServer to static IP. (It did get an IP from DHCP so I could get into the web server in the box)

Other than this hiccup which is mainly my fault, I’m impressed with how well the serial data is being translated. The PortServer is able to pick up on “on-the-fly” serial port settings changes. We do things like flipping the 9th bit from mark to space for address/command flags and the changes are sent through as expected.