I happen to be trying to interface with a TDK Lambda Z+ instrument as well right now. After a week I figured something out. This is for a z100-8-u model. I wanted to get SCPI to work, but I found a way to get the GEN protocol to work, which is what you need.
Download the USB driver for the Z+ unit here, Z+ USB Drivers Download Zip. or find it on the webpage, https://uk.tdk-lambda.com/technical-centre/software-tools.aspx
plug in a USB cable from your computer to the unit.
Setup the unit for Interface-USB, BAUD-9600, LANG-GEN, ADR-6
Start a default Putty session and change the following parameters.
Set connection type to serial line to COM("""this number will be based on your computer""")
Go to terminal and check, "implicit CR in every LF", and "Implicit LF in every CR". Also, under line discipline options, make sure local echo is "Force on"
Under connection>serial>Baud-9600, data bit-8, stop bit-1, parity-none,flow control-none.
Start the session
It should be a blank screen, but it shouldn't exit out.
Type the following to get started:
"OK" should be returned.