VICI EUT Universal Electric Actuator - Manual (Page 20)


Optional BCD Interface
Hardware Input / Output Protocols
The digital interface is made through a
26 pin connector which also provides power
(+5 volts/100 ma maximum) and ground out-
puts. The ground should be connected to the
control system to maintain commonality
between the actuator and the controlling
device. If you intend to provide your own power supply,
make sure that it has an isolated output or that it shares a
common ground with the controlling system.
Digital input/output control of the actuator is designed for simplicity and flexibility of
function. The simplest control of the actuator can be accomplished in modes 1 and 2
with a single control line for the STEP function. Mode 3 requires only two output control
lines – STEP and HOME. The chart on the next page lists other control options.
The inputs are held to a logical high (+5 volts) by pull-up resistors, and are designed to
be driven low either by contact closure, 5 volt digital logic, or open collector transistor
outputs. The signal polarity is defined as “negative true” – asserting the signal involves
shorting the signal (in the case of contact closure) or driving it (in the case of logic or
transistor signals) to within 0.8 volts of ground potential. These input signals must be
at least 30 milliseconds in duration.
The outputs are also “negative true” signals driven by standard high speed CMOS gates,
capable of driving standard logic input gates. They include the BCD position, motor run,
rotational direction, and error signals. If the actuator stops out of position due to a stuck
valve, the BCD output is set to “0” (all lines high for a negative true output).
Digital Input Protocols
The input modes are selected during factory setup/programming.
Binary Coded Decimal (BCD) input mode (default)
For the 96 possible input positions, all 8 digital input data lines are required. Refer to the
chart on the next page for the signal line definitions.
Parallel Input Mode
In this mode, the data input lines are redefined so that each input line equates to only
one actuator position; any and all combinations of data input lines are invalid. This mode
can support only 8 positions: 1 BCD = position 1; 2 BCD = position 2; 4 BCD = position 3;
8 BCD = position 4; 10 BCD= position 5; 20 BCD = position 6; 40 BCD = position 7; and
80 BCD = position 8. The offset value SO is set to 1, and since the number of positions
is limited to 8, any user-set NP value greater than 8 will revert to 8. (See the chart on the
next page for more explanation of NP and SO.)
Binary Input Mode
This mode allows up to 128 possible input positions. All 8 digital input data lines are
required. Refer to the chart on the next page for the signal line definitions.
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Figure 11: Digital I/O
connector on rear panel