Specifications

Sicon-8 Technical Manual CircuitWerkes, Inc.

Metering & Status Connections

Metering

Eight metering channels are brought into the Sicon-8 on a depluggable euro-connector located at the center of the back panel

(see Figure 2 above). These analog inputs can handle either positive or negative voltages of up to 12 Volts, however all inputs must

be ground referenced by connecting your metering ground to the Sicon-8's ground. To make setup and operation simpler, each input

is auto-ranging. You do not have to adjust any potentiometers to set the proper input range. Inputs are self-calibrating and are based

on an internal, precision, low-drift, voltage reference, so the meters will not drift over time or with temperature. Metering setup is as

simple as connecting the sample voltage and then telling the Sicon-8 what the input voltage represents. DO NOT CONNECT SAMPLE

VOLTAGES IN EXCESS OF 12V OR DAMAGE MAY OCCUR TO YOUR SICON-8. Although not optimized for this, metering inputs

are sensitive enough to allow them to be used to monitor audio levels for silence detection. Attach an audio source to the metering

input of your choice and calibrate that input for 100% and you will see the meter deflect with audio. Because audio samples are often

very small, the metering input may not reach zero when the audio sample is removed. This is due to small offset voltages that occur in

the input buffer amps. Silence alarms must be set to some point above the nominal noise floor. The frequency response of the inputs

is also intentionally limited to a few hundred Hertz for rfi suppression, so measured audio is skewed to the bass end of the band.

Floating Grounds

Except for status input #8, none of the Sicon-8’s metering or status inputs will accept a floating ground. Damage to the Sicon-8 or your

equipment may result from connecting a floating ground output to the Sicon-8. If you must use a metering or status inputs with

equipment that has a floating ground, an isolation amplifier must be used.

Status

The Sicon-8's optically-isolated status inputs can be used to determine the status (on/off) of your equipment. The

status input connector is located immediately to the right of the metering connector and the first seven status channels

accept only contact closures as inputs. If the voltage at the input is at or very near ground, then the status channel is

considered active, and if it is ungrounded, the channel is considered inactive. The logic can be reversed on each channel,

in firmware, so that the status is considered active when ungrounded. You can also choose to disconnect the Sicon-8's

internal 5V supply and source your own Voltage (up to 24V) to inputs 1-8. To Source Voltage, you must first move the

“PWR SEL” jumper (JP517) from “Int” to “Ext”. Be sure to never jumper both simultaneously. Then you connect your

Voltage source to the Ext input and ground of the “Stat Pwr” (JP-525) connector located just to the right of JP517. Internal

5V is also brought out to the “Stat Pwr” connector should you want to use it for powering temperature probes, etc. Never

connect up an external Voltage source to the status inputs without moving Jumper JP517 to “Ext”. Regardless of whether

you use the internal Voltage source or your own, your equipment's ground must be tied to the Sicon-8's ground.

In addition to the ability to source an external Voltage to the status inputs, the eighth status channel provides some

additional flexibility. Based on the “Ch8 SEL” (JP-517) jumper setting, you may configure channel 8 so that your

equipment sources current to or sinks current from the Sicon-8. In either case, if current is flowing, then the input is

considered active, but again, this may be inverted according to your preferences. If both jumpers are removed from JP-

517, you can supply your own, floating Voltage to channel 8’s + and – inputs. The factory default configuration is set to

activate when the minus (-) input is tied to ground. In the default configuration, the plus (+) input should be left floating. If

you don't want to source your own current to status channel 8, one line is provided with +5 V. This line is diode-protected

and current-limited. It is not required that a +5V line be used to source current to channel 8. It will tolerate up to 24 VDC

as input, but at least 3 VDC is needed to turn the optoisolator on. The status inputs will not accept AC Voltages. If an AC

input is required, a bridge rectifier with a small capacitor at its output should be used to convert the sample to DC before

connecting it to the Sicon-8's status input. As noted above under metering, except for status input #8, connecting a

floating ground to your unit may result in damage to the Sicon-8 or the device that is connected to the Sicon-8. It may also

result in erroneous readings or status indications. An optional status input converter board is available to interface status

Fig. 2 - Sicon-8 Back Panel Diagram

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