prh-ZG1 Random generator


PRH-ZG1 is used for controlling personnel staff.

You only need to connect the floating contacts of a card-reader, which connect a turnstile, with the unit ‚prh-ZG1‘. With the help of a potentiometer you can adjust the average number of persons which are to be controlled (e.g., 1% up to 50% means, that only every (average) hundredth (1%) or every (average) second (50%) will be controlled).
The en- or disabling of a pass is implemented as a floating contact of a relay (for each case one two-way contact), connected to six terminals on the special housing, that means 3 terminals for ‚red‘ (no pass) and three terminals for ‚green‘ (pass o.k.).
You only have to feed the signal ‚green‘ to that point, where you have connected the card-reader without control of personnel staff formally.
If the unit ‚prh-ZG1‘ decides ‚red‘ (no pass) in response to the pulse of the card-reader, you can see the multi colour LED on front-panel lightning red as well as you can hear a beeper inside of the device. Additionally you can use the terminals ‚red‘ (two-way contact) to connect other units (PC, siren etc.). When the enabled terminals (green) are in the case of ‚red‘ inactive, nothing happens, that means, the person cannot pass a turnstile e.g..
As the name ‚Random Generator‘ says, the passing is controlled by an internal micro controller, which is calculating the random numbers. If e.g. the potentiometer ‚rate‘ is turned to 50%, it is also possible, that e.g. ten passes in a row are calculated ‚red‘, but the average upon several hundreds will show the adjustment of the rate ‚50%‘. Therefore it is impossible for the staff, to calculate the individual chance for passing, even by an adjusted rate of 50%

Prh-ZG1 is housed in a stable box with ten integrated terminals and also provide connection to a (German DIN) mounting rail.
W x H x D: ca. 46 x 75 x 127 mm (W = system-width according to the DIN-mounting rail of type TS35, see picture)

Power supply
prh-ZG1 has to be supplied with +24 volt DC and consumes ca. 0,1 Ampere. The according terminals are labelled with ‚+24V‘ and ‚0V‘.

Signal input
The pulse input (the signal comes from a card-reader e.g.) is via optocoupler galvanic-free from the rest of the prh-ZG1-electronics. The active state (current flows through the diode of the optocoupler) is indicated with a blue lightning LED on the front panel.
There exist two possibilities of connection : 1. High active : switch between terminal ‚+24V‘ and ‚+in‘ and short ‚-in‘ with ‚GND‘, or 2. Low active : short terminal ‚+24V‘ with ‚+in‘ and switch between ‚-in‘ and ‚GND‘.
Also possible is the use of an galvanic free control voltage of +24Vdc, to source the current of ca. 10 milliAmperes through the optocoupler-diode.

1. The terminals ‚+24V‘ and ‚0V‘ are simultaneously used as power supply for the internal electronics of prh-ZG1.
2. Attention: The galvanic separation between input and prh-ZG1 electronics is not to be used as the only separation to mains because of personnel health. In that case you have to interface coupling relays which allow to separate mains (230Vac) to low voltage (+24Vdc) potential.

There are two outputs according to ‚red‘ and ‚green‘ as separated floating contacts (two-way), connected to six terminals.
The internal relays-contacts are allowed to separate potential of only max. 50 volts and 1 ampere load.
Attention : for connection to circuits with higher voltages (as e.g. 230 volts) you absolutely need additional coupling relays which allow to separate such potential differences !

‚pass‘ = green = pass without control, the pulse width can be adjusted between 0,1s and 3s continuously by a potentiometer.
‚Test‘ = red = no passing, the pulse width can be adjusted between 0,1s and 6s continuously by a potentiometer.

Average rate of control
The number (‚rate‘) of persons which are to be controlled can be adjusted by a potentiometer continuously between the averages from 1% to 50%.

Random rate
The number (“guess/advise”) of persons which can be controlled is infinitely variable adjustable between 1% and 50%.

One multicoloured LED shows as follows :
yellow : operate ‚Power On‘ as well as the state of waiting for an input pulse (e.g. from a card-reader)
red : The output relays ‚red‘ are active
green : The output relays ‚green‘ are active
One LED ‚blue‘ lights while a current flows through the active optocoupler diode. This shows the momentary active pulse (e.g. from a card-reader).