Speaking of Vex (specifically the Cortex and VEXnet control system),
-I recently FTA'd a small qualifier (24 teams) in my high school gym. I used three 1.4ghz Celeron laptops donated to me by the school when they got new ones and were literally throwing the old ones that still worked away. One ran the field and audience projector, one ran the skills challenge field, and one ran the two pit displays (rankings on the projector, SC rankings on the laptop screen). We never had any field issues with the scoring computer at all, and ran only one test match. All issues were solved by plugging in the cables or replacing the VEXnet keys (they seem to fail when they heat up a lot after an hour or so of running continuously, but it's not a permanent failure). We did not have a field delay EVER. The DJ (a FIRST student) told me he had a list of dancing songs, and couldn't play them because the field worked all the time. VEXnet is based on 802.11, has connection times under 20s, and allows radio use in the pits.
-The entire cost of the VEXnet field controls was sub-$200 for all of the field control electronics and cabling, plus the requirement for a WinXP laptop. You can download it from
http://www.dwabtech.com/main/tm2/ and play with it to answer any of your questions.
-We also use the VEX Cortex control system in OCCRA, where the robots are similar to FIRST:
-115lbs including battery, extra 5lbs if you use pneumatics with the on-board compressor
-no bumpers
-28x38 footprint by 40" tall
-Motors include CIM motors, DeWalt drills, and various automotive window, wiper, van door, seat, etc. motors
-Our Cortex was right in the middle of our robot, in a fairly bad place for interference. This is due to an OCCRA rule requiring all electronics to be in a box for protection of the electronics, and the only place the box would fit was exactly in the center.
-At OCCRA, they had very few field issues all season, and the OCCRA field staff was very good about checking all robots communications before each match, and diagnosing all failures. In OCCRA, there are 8 VEXnet systems on the field at a time, plus any teams running VEXnet in the pits (which is allowed).
As some of you asked about the FRC FMS, here is what I can tell you (I know this is certain):
-The Scorpion Case has a PLC and the FMS server, both connected via Ethernet
-The Cisco AP, sitting on top of the Scorpion case
-The blue start/stop button box, connected via Ethernet
-The SCC's (Station Control Cabinet) sit at each alliance station, and contain:
--Allen-Bradley hardware including an industrial Ethernet managed switch
---This has ports for the Scorpion case, each robot DS, and the switch below
--A generic Ethernet switch - This is for all of the Allen-Bradley remote IO at this end of the field, such as any lights or e-stops or sensors
--Various Remote IO boards for all of the IO at each end of the field, all communicating over EtherNet/IP
-The ref tablets are Allen-Bradley touchscreens, also connected via Ethernet.
-Each driver station is VLAN tunneled to it's virtual WiFi network on the Cisco AP. The rest of the field runs VLAN's for its own use, I believe only one but I am not certain.
Edit: More information
-The lighting on the bridges is DMX controlled, via DMX-Ethernet bridge which is connected to the Ethernet switch on one of the SCC's
-The lighting on the driver stations is controlled via the Remote IO boards
-The bridge sensors are also connected to Remote IO boards
-All of the wiring to the bridges runs under the barriers/bumps. They act as conduits.
-The blue box just duplicates software buttons and the field can run without it
I won't attempt to explain any software, as I'm not an FTA and can't verify my knowledge.