104 C4 Manual Rev 7.5.2
train your users to use their finger to discharge the static potential they may have
accumulated on something other than the C4 front panel.
9.7.4 Noise Immunity
Noise can show up as lost or incorrect data sent over the bus. In extreme cases
this noise can disrupt controller operation regardless of whether computer bus is
in control or not. The following modification has been found to solve many
computer bus related noise problems. It will provide static ground to the
backshell of the IEEE 488 bus connector as well as pin 1 of the EIA-232 connector,
bypassing any path through the digital circuitry. It is not done at the factory
because in some cases it actually degrades noise immunity by creating a ground
loop.
Bus static ground connection is made as follows: Solder a short green 22g. wire to
the A-Board static ground eyelet located below the IEEE-488 connector. Hook the
other end of the wire to a horseshoe lug and connect it to the main terminal strip
J1, lug #3. (green).
9.7.5 Diagnosing and Solving Local Mode Problems
Controller starts immediately in Local Mode
If the system improperly begins controlling to the setpoint when you turn the
controller from OFF to LOCAL Mode, before you press <START/STOP>, the
Autostart setup parameter (F14) is set to enable Autostart. Resetting this setup
parameter to 0 will disable the automatic starting feature.
9.7.6 Diagnosing and Solving Program Mode Problems
Hard Loops
Also note that hard loops will execute forever. Standard loops, using the loop
command, do not allow nesting. Only one loop may be active at a time. If you
have a nested loop, it may appear to function properly, but it will probably never
complete.