3.6 RS232 control
AdderView GEM can be controlled by a remote RS232 device. To select a channel the data rate of the sending device must be set to 1200 baud, 8 bits, no parity and 1 stop bit. No handshaking is used by the AdderView GEM. Simply send the character for the channel which needs to be selected, for example ASCII ‘1’ (hex code 31) will select channel 1, ASCII ‘2’ (hex code 32) will select channel 2 and so on. The AdderView will echo the ASCII character back to the sending device when the channel has been changed. The serial interface pins are found on the options connector on the rear of the AdderView. Pin assignments for this connector are given in appendix A.
3.7 Cascading AdderView GEMs
AdderView GEM switches can be connected together to expand the number of connected computers. When cascading AdderView GEMs a power adapter (AVGPSU) must be connected to each AdderView GEM. AdderView GEMs can be connected in a cascaded tree structure. This can be particularly useful where clusters of computers are located some distance from each other because each unit acts as data booster and can each be up to 30 metres away from the next AdderView GEM. The channel can be selected on remote AdderView GEM units using an extension of the HOTKEY control .
For example, consider a situation where two AdderView GEM units are connected together as shown below. To connect to the computer attached to port 3 on AdderView GEM B the user would hold down the hotkey keys then press ‘2’ followed by ‘3’, whilst keeping the hotkey keys pressed. This will have the effect of connecting to port ‘3’ of the AdderView GEM which is connected into port ‘2’ of the first AdderView GEM unit A.
For example to connect to port 3 on the AdderView GEM cascaded off port 2 of your first AdderView GEM use:
press ba2release 2
press 3release 3ba
AdderView GEM | Installation and Use | Page 24 |
