|
|
|
![]() |
|
|||||||
|
||||||||
|
|
Thread Tools | Rate Thread | Display Modes |
|
#1
|
|||
|
|||
|
Relay Connection Figure 2.2 in error ?
In THE ROBOT, page 10, in 2.1.3 Relay Modules, Figure 2.2 purports to show the connection for "independent control of two devices from a single relay module", where the obviuos candidates for 'device' being pneumatics valves.
The manual shows one device connected between + (presumably +12V) and one of the relay terminals (say M+). The other device is connected to - (presumably the - battery terminal (or 0V). When the power goes on, with no relay active, device one is ON, since both M terminals are at 0V (in a Blue Spike). If the 'fwd' of this realy is activated, M+ will go to +12V and the valve will go OFF ! Not intuitive ! Notice that the +12V input to the relay is the fused line, and has a fuse block breaker in deries with it. When Device 1 is ON, the only breaker in the circuit is rated at 60A. The wire to the device, if injured by grabbing or collision, is only 16 ga. wire. Incandescense at 200A, anyone? ![]() As for the other device, it will be between +12V through the M- terminal and OV via the return on the fuse block, when the 'rev' signal is sent. This is reasonable operation: '1' for ON, '0' for OFF. SOLUTION If both valves were returned to ground, then one valve would come on when 'fwd' = 1, and the other would come on when 'rev' = 1, which would be a saner way to run a robot. Another big problem is that connecting to the fuse block, according to the checklist of Update 4, is a No No. A couple of urgent changes ? A complication: the Red Spikes are arranged to rest on +12V, not 0V. the circuit would have to be re-arranged for them, with coils returns going to the fuse block breakered + terminal. Even in the circuit from the book, though, neither device would be so grossly unprotected as with a Blue Spike. I wrote to FRCtech2002 but it may take some time there to go through. |
| Thread Tools | |
| Display Modes | Rate This Thread |
|
|
Similar Threads
|
||||
| Thread | Thread Starter | Forum | Replies | Last Post |
| Relay Outputs | OddOne | Technical Discussion | 3 | 01-02-2002 19:52 |