I have connected with USB and Ethernet from one PC before, never tried from two different machines I would suggest just trying it.
For the second question make sure that the PC and PT104 are on their own private subnet, try pinging the unit first to verify ethernet connectivity, and if you are using your own application make sure that you use both ipaddress:port and the serial number when using the open unit command.
I am trying to connect with USB and Ethernet both at the same time on the same laptop, but to no avail.
I am even trying to connect only with ethernet cable, but to no avail. The instrument is not getting detected.
I went into Ehternet settings, and entered the IP address as 192.168.1.70 and port as 8080. Also tried with other ports as well.
After saving the settings, when I am opening the picolog recorder and selecting PT-104 (Ethernet), it is not detecting the unit. I even tried punching the IP address and port in the bottom of the same screen, but to no avail.
I have modified the IP address of my Lan port to the same as PT-104 IP address.
Then re run the EthernetSettings utility and reset the ip address (192.168.1.70) and port (6570), not 8080 which is a second http port, and try pinging again.
There is no ethernet address on your pc for 192.168.1.x which can talk to a PT104 configured as 192.168.1.70 as the ethernet adapter has defaulted to a Microsoft 169 address, 169.254.74.170(Preferred). This will have been issued when it failed to get a DHCP one.
Please check the network configuration for your ethernet card, turn off all other networks on the pC, including your wifi, and try again. Possibly even use 1:1 cables plugged into a hub.
Until you can ping the device you will not be able to talk to it.