VICI Selectors (multiposition) Microelectric - Manual (Page 4)

4
Simultaneous Use of the Manual Controller and an External Control System
The manual controller has two identical connectors for input and/or output, permitting an external
system to be used simultaneously with the manual STEP and HOME commands. However,
the
following precaution should be observed:
If the STEP and HOME functions are to be used by both systems, the external system control output
cannot be in the form of TTL signals; instead, the output must be a momentary signal asserted by a
contact closure or open collector driver. While TTL signals will cause no damage to either system,
they will effectively override the manual controller.
Connecting External Systems
An external control system can be connected to the actuator in several ways:
1. The Digital Input/Output connector is a 26 pin dual in-line connector which can mate to a mass
terminatable flat cable connector available from a number of manufacturers. The flat cable can
then be integrated into the control system.
2. The manual controller can be connected to the control module, and then a 26 pin dual in-line
connector and flat cable assembly can be attached to the manual controller. This allows dual
control as well as a visual indication of the actuator position.
3. A serial port can be connected from a host control system to the actuator, using the optional
RS-232 cable (Product No. I-22697).
Digital Protocols
Hardware Input / Output Protocols
Digital input/output control of the multiposition actuator is designed for simplicity and flexibility of
function. The simplest control of the actuator can be accomplished with 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).
The digital interface is made through a 26 pin connector which also provides power (+5 volts/100 ma
maximum) and ground outputs. 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.
Software Input Protocols
(chart on next page, discussion on page 6)