Serial Port / Hardware Setup

Synergize relies on a connection to the Synergy through a serial cable - which is unusual in this era of computing. Many of us have not had to configure a serial cable and think about baud rates for decades (and some perhaps never have). Here’s a description of what needs to be done to connect Synergize to your Synergy. See Troubleshooting for some procedures to diagnose problems if the settings on this page don’t seem to be working.

Synergy-side configuration

Baud Rate

The Synergy’s serial port baud rate is configured with a hardware jumper on the serial interface daughter board. The settings must match the baud rate setting in Synergize.

Data bits

The Synergy always communicates with 8 bits and one start and stop bit.


By default, the Synergy is configured for “no parity” and that is how I have tested the serial connections. However, this is configurable via buttons on the front panel of the Synergy: Press RESTORE RESTORE and the LED’s in the Channel Assign button display the parity settings. The Channel Assign button can be used to alter the parity setting while in this mode.

Channel Assign Parity
Both On No Parity
Left On Odd Parity
Right On Even Parity
Neither On Error detected on serial board

Flow Control

The Synergy uses DTR and CTS (“hardware flow control”).

My configuration

My development and testing setup is a mix of direct connections and virtualized environments, so they may not be directly useful to you, but I’m listing them here to give you concrete examples things that work for me.


My Synergy is configured at 9600 baud and no parity as shown above. I’ve tested successfully with 19200 but my day to day use is at 9600 baud.

Serial Cable(s)

The connection from the computer to the Synergy requires a “null modem” cable. I test with a combination of a traditional null modem cable (same type you would use for a direct SYNHCS/Kaypro connection) and an FTDI based USB serial cable.

I’ve been asked specifically what cables I use. I’ve been told that FTDI makes the most robust chipset, but I have NO objective reason to prefer one cable over another. These are not “endorsements” - it’s just a note of what “works for me”:

MacOS (Monterey)

This is my primary development environment; it’s tested natively:

Environment Device Baud Rate OS Serial Config
MacOS (Monterey) /dev/tty.usbserial-AL05OC8S 9600 n/a

Windows 10

This is tested via a virtual machine running in Parallels on the Mac. Here there are three sets of settings - the Parallels virtual machine, and the Windows OS and Synergize itself. Note that I run Synergize at 9600 to match my Synergy, but the virtualized Windows OS is configured at 19200. Also note that I’m using the cu variant of the unix serial port rather that the tty variant.

Environment Device Synergize Baud Rate OS Serial Config
Parallels VM Serial Device: /dev/cu.usbserial-AL05OC8S    
Windows10 COM1 9600 Device Manager: 19200 baud, 8 bits, No parity , 1 stop bit, hardware flow control

Linux 64bit

I test the 64bit Linux version via Parallels. Ensure your user is a member of the dialout group.

Environment Device Synergize Baud Rate OS Serial Config
Parallels VM Serial Device: /dev/cu.usbserial-AL05OC8S    
Ubuntu 18.04 /dev/ttyS1 9600 n/a

Linux 32bit

My 32bit linux environment is raw metal (an old laptop with a real serial port). So no USB serial cable involved - just the null modem cable plugged into the serial port. Ensure your user is a member of the dialout group.

Environment Device Synergize Baud Rate OS Serial Config
Ubuntu 16.04 /dev/ttyS1 9600 n/a