This could be a cable issue. Some of our cables are designed for 3-wire connections and loop back other signals so that whenever the cable is plugged in, it looks like there is a device connected to the other end of the cable. In this case GEMS would never be able to see whether the Accu-Vote is really connected and powered on.
Global may have had some three wire cabling in the Vancouver office but I don't know of any customers that use that configuration. We usually shipped standard computer cables to customer sites.
BTW, the Accu-Vote main serial port does have an input for hardware handshaking. Pin 8 on the DB 9 pin connector is attached to a CTS line (true high on the DB 9 connector) into the V25 CPU chip. That is unfortunately the only line available on the V25 CPU chip for data flow control.
The modem port does not have that line connected to the modem. The CPU board Revision 6.1 (current) and lower has that line hardwired in a true condition for the modem port.