I don't think that's a real null-modem cable, I think it's a straight-through cable. It has RX to RX and TX to TX, and you need those swapped for null-modem use. You can add a null-modem adapter on the 9-pin side and it should work fine, that's what I have on my setup (USB to Serial -> Null Modem -> 9-to-25 adapter)
On Sun, Jan 18, 2026 at 11:05 AM Erik van der Tier <[email protected]> wrote: > > Hi, > > I’ve been trying to get my T102 to talk to my modern MacBook. For this > I’ve bought a usb-c to db9 cable and a db9 to db25 serial null modem cable. > I have today installed a REX# in my t102 as well. > Anyway, I haven’t been able to get a connection to a terminal program nor > TS-DOS. I know this *can* work on a Mac as I”ve previously had a T102 and a > pretty crazy franken-cable that work like a charm. > > This time I though, I’d get a simpler setup with only one usb-c to serial > and a null modem cable, in stead of a USB-A to serial, a DB9 serial modem > cable, a null modem converter and a DB9 to DB25 converter. Crazily enough > that horrible mess of cable and multiple adapters worked. > > The serial cable that I got this time around is this one: > https://www.amazon.nl/Vrouwelijk-parallelle-printerkabel-Datatransmissie-Communicatie/dp/B08C9TXXCK/ref=sr_1_18?__mk_nl_NL=%C3%85M%C3%85%C5%BD%C3%95%C3%91&crid=TRBHXQVKSIVH&dib=eyJ2IjoiMSJ9.NOI_htfBsniWi16cA7NrpAsbwAFQHVL9HsjtCZDB-QrcH328-7sC_CZHghnU9G19bemEAqjGO2AYpuVod7RPWDwXiMs-6romUKb81fCynFFx7v8y0LYEfR77WCc9mMFZOu_J2ZEZXMmzgzG4UVOAP2-9q0vmmPaW_Ko3ivHRWYh5ZifAD_7KLGEqK7aFxOn22KcARopde7vuFHpTzbvko1rPviFqUyTirH8GS7y8mj4GWrIXFhwTAiFCo6ZOaSuwTLUTNk1apT1lg5p8hgHYLzKCiN7PfDL-dWWzZUZDUfE.wnq2KLE6yCDlC49ZLZqqn82UL8RLijAKlOy-veK9Jtk&dib_tag=se&keywords=Tripp+Lite+Model+P456-006+6+ft.+Null+Modem+DB9F+to+DB25M&qid=1768668965&sprefix=tripp+lite+model+p456-006+6+ft.+null+modem+db9f+to+db25m%2Caps%2C113&sr=8-18 > . > > I don’t really know much about serial cables and connections, so I’m > having a hard time debugging this setup. Does anyone of you have an idea of > what’s wrong, or what serial null modem cable that can be ordered in Europe > and is know to work? > > Cheers, > Erik >
