The EDM uses an RS232 connection back to a PC for communication. DB9 Male to Female cable is generally what is required. A [NULL modem cable](https://en.wikipedia.org/wiki/Null_modem) is generally a Female to Female cable that has pins 2 and 3 swapped so that two computers can talk to each other. [AMPLIMITE D-SUBMINIATURE CABLE ASSEMBLIES](https://docs.rs-online.com/c9fe/A700000011251493.pdf) from TE look to be a reasonable product. - 5ft, 26AWG, [2478170-5](https://www.te.com/en/product-2478170-5.html), RS:[287-6291](https://au.rs-online.com/web/p/serial-cables/2876291?searchId=a45e1e71-084f-4423-84d4-b867dab0f568) - 6ft, 28AWG, [2478170-7](https://www.te.com/en/product-2478170-7.html), RS:[287-6293](https://au.rs-online.com/web/p/serial-cables/2876293) - 10ft, 26AWG, [2478170-6](https://www.te.com/en/product-2478170-6.html), RS: - 10ft, 28AWG, [2478170-8](https://www.te.com/en/product-2478170-8.html), RS: - NULL, 6ft, 28AWG, [2478170-3](https://www.te.com/en/product-2478170-3.html), RS: Pro Signal cables are significantly cheaper from E14 - M to F, 0.5m, PSG90866, [E14](https://au.element14.com/pro-signal/psg90866/lead-9way-d-female-9way-d-male/dp/3409546):3409546, $4 - M to F, 1m, PSG90867, [E14](https://au.element14.com/pro-signal/psg90867/lead-9way-d-female-9way-d-male/dp/3402706):3402706, $8 - M to F, 2m, PSG90337, [E14](https://au.element14.com/pro-signal/psg90337/lead-joystick-extension-9way-2m/dp/3402473):3402473, $7 Null Modem Cable - F to F, 2m, [VIDEK:](https://www.videk.co.uk/section.php/1348/1/rs2323-serial-file-transfer-cables)4070, [E14:](https://au.element14.com/videk/4070/lead-null-modem-9way-d-skt-skt/dp/1525913)1525913, $7 ## USB to Serial Converters We have tried many different converter cables over the years. Some are more reliable than others. There are several different manufacturers that provide these cables. There are fewer companies that provide the actual converter ICs for these cables (FTDI, Prolific, etc). There is an IC inside the cable which provides the electrical conversion parts. But there is also driver software that runs on the PC that provides the interface between the IC and the computers serial port interface. There can be issues over time with drivers (some are better than others). None of the manufacturers have been perfect. However FTDI has been the most reliable over time for our specific case. USB-C is another challenge. I haven't found a cable with USB-C that has worked reliably yet. RS has a [USB-C cable](https://au.rs-online.com/web/p/serial-converters-extenders/2284347?cm_mmc=AU-GDN-DS3A-_-google-_-AU_EN_GDN_Dyn_Remarketing-_-General+Visitors+30days-_-&matchtype=&aud-386146035351&s_kwcid=AL!7457!3!386636470496!!arstechnica.com!d!!&gclsrc=aw.ds&gclid=EAIaIQobChMI_LnW0MDW-AIVzEl9Ch1x7AnNEAEYASABEgLo3fD_BwE) that uses FTDI chips. https://www.amazon.com.au/Serial-Adapter-OIKWAN-Built-FT232RL/dp/B08B5M1KBZ?th=1 https://tips.graphica.com.au/macos-big-sur-rs232/ FTDI still don't produce a USB-C to RS232 cable. All the others that I have found with FTDI chips don't include TX and RX LEDs in the cable (which is very convenient). The following cables are still the best that I have found. They had RX TX LEDs and use the FTDI chips. One is 1m long and the other is 10cm long. They need a USB-C to USB-A adaptor as well [Apple:USB-C to USB Adapter](https://www.apple.com/au/shop/product/MJ1M2AM/A/usb-c-to-usb-adapter). - 1m, [FTDI:US232R-100-BLK](https://ftdichip.com/products/us232r-100-bulk/) [RS:687-7806](https://au.rs-online.com/web/p/interface-adapters-converters/6877806) - 10cm, [FTDI:US232R-10-BLK](https://ftdichip.com/products/us232r-10-bulk/) [RS:429-274](https://au.rs-online.com/web/p/interface-adapters-converters/0429274) ## Serial Port Isolation The [MOXA TCC-82](https://www.moxa.com/en/products/industrial-edge-connectivity/serial-converters/serial-to-serial-converters/tcc-82) is a good isolator. It doesn't require an external power supply. [Fastron](https://fastron.com.au/products/tcc-82) [Colterlec](https://colterlec.com.au/product/moxa-tcc-82/)