500-004941-000
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maximum tracking rate of the converter, there is one overshoot (which is inherent in
a Type II servo). The overshoot settling to final value is a function of the small
signal settling time.
Resolution control is via two logic inputs, A and B. The resolution can be
changed during converter operation so the appropriate resolution and velocity
dynamics can be changed as needed. To insure that no race conditions exist
between counting and changing the resolution, inputs A and B are latched
internally on the trailing edge of CB.
Direction Output (U) is a logic "1" to count up and logic "0" for down. The
logic level at (U) is valid 0.5 µs before and 0.5 µs after the leading edge of CB.
Either low or high bandwidth can be selected by using the BW logic input.
A logic "0" applied to BW will select low bandwidth (130 Hz nom.); a logic "1"
selects high bandwidth (530 Hz nom.). Bandwidth can be changed during
converter operation.
3.4.6
Dynamic Performance
A Type II servo loop (Kv = •) and very high acceleration constants give
the RDC-19200 superior dynamic performance, as listed in the specifications. If the
power supply voltages are not within the ±15 VDC nominal values (5%), the
specified input rates for full accuracy will increase or decrease in proportion to the
fractional change in voltage.
3.4.7
Built-in-Test (Internal to the Converter)
The RDC-19200 provides two useful logic outputs for systems self tests.
The Built-In-Test output (BIT) monitors the level of error (D) and, if it exceeds
approximately 65 bits, the logic level at BIT will change from logic "1" to logic "0".
This condition will occur during a large step and reset after the converter settles out.
BIT will also be set for an over-velocity condition because the converter loop cannot
maintain input/output sync, and if the converter malfunctions where it cannot
maintain the loop at a null. For system safety, the Loss Of Signal (LOS) output is
useful. The LOS signal will change from logic "0" to "1" if both resolver inputs are
disconnected, resulting in unpredictable converter performance.
3.5
BUILT-IN-TEST (ON-BOARD)
The Built-in-Test feature of the VMIVME-4941 requires a separate digital
to resolver converter board. Built-in-Test is performed under software control in
which the D/R output board is used as a resolver input for the VMIVME-4941. The
VMIVME-4941's CSR is programmed to connect all four R/D modules to the P2
resolver input channel. Thus, a digital word is transferred to the D/R board and can
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