If you have a Monitor III or other alarm dialer connected to the system for monitoring, there is usually a port on there that you can connect your admin PC to for normal administration. If there isn't, some of it will depend on which Hicom 300 you have and what OS version is on it. If you have Model 80, which is the size of a refrigerator, there will be 4 serial ports on the lower right side of the back of the cabinet. If you have 9006.6 OS set the serial port to 115200 8 N 1, hook a normal serial cable to one of the ports and press Enter a few times. If you get a login prompt that is the right port. It may also be labeled. If you are looking for the RMX port the settings for that are 4800 7 E 1 and you usually need to use a null modem adapter when connecting to that one (I might have that backwards, but one of the ports needs a null modem cable or adapter). The RMX port might also be used for CDR output on some systems. If you have a version of 9006 older than 9006.5 it is probably 19200 8 N 1 and really old versions used 9600. 9006.5 was a weird beast and came in 2 flavors - both of which run at 38400 I believe. RMX is always 4800 7 E 1.
If you have a Model 30 the serial ports are usually inside, underneath the cards on the left. I have connected to them before but it has been a lot of years. I know on newer 9006.5 and 9006.6 hardware you could access either RMX or Unix by connecting to the system port on the front of the processor board, and one of the serial ports inside the cabinet was the other one, and I think needed a null modem. It has been almost 5 years since I've done all that stuff so I'm getting really rusty!
Don Bruechert, Voice Comm Analyst II
CareTech Solutions @ Holy Family Memorial
Manitowoc, WI, USA