Tetrix servo controller doesn't work well

[jerry_dcjx]

I'm going to use 4 DC controller and 2 Servo controller this year, and i just tested the system today. those DC motors works pretty good, but the servos works in a very strange way.

I connect 2 HS-755HB and 1 HS-785HB to the first controller in port 2, and 2 y-line which control 4 hs485hb and 2 hs485hb seperatly connected to the second controller of port 2.

When i try to move the servos on the second servo, some problem happens. the first problem is nomatter i command which servo on controller 2 to move, the chan3 and chan4 will locked to about 120degree. And sometimes i make a command for chan1 & 2, then chan 3&4 moves.

I don't know what happens, but the first servo controller works well. Now the second controller is totally working randomly. How can I solve this problem? Why this happens? is there any team met the same situation like that?

[mathterizer]

This has been happening for us as well. (As far as I know, it occurs with  RobotC too.)  We refer to it as servo bleed-over.

This is how we've been handling it:

• In Schematic Editor - when we are testing/prototyping an individual servo we find it best to physically disconnect the servos we don't want to move (if it is an issue). We like to use S.E. to determine our servo numerical positions.
• In RC Editor - not a lot you can do here if you are working in Prototype mode; physically restrain servos that could present a problem with the bleed-over.
• Generated Code - We modify the generated RC vi so that whenever one servo is activated, ALL servos are sent the desired values.  We create a control variable for each servo and keep track of the most recent servo position.
• Autonomy vi's - As mentioned above...whenever we activate one servo we send the desired position to ALL servos. We keep track by haveing a control variable for each servo.

Hope this helps!