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P

Panel frame
Module frame for a counter

Parallel interface
Transfer point at which the data are transferred in parallel over several lines.

Parity
Checkbit for error detection in data transfer

PDO
Process data object (in CAN networks)

Period measurement
Time measurement; the time is measured for the duration of one period (pulse + separation). The display is updated in cycles.

P/E converter
Preset counter with pneumatic count input and electrical control signal generation (see pneumatic preset counters)

Phase discriminator
Sense-of-direction detector that functions by evaluating the phase angle between Signal A and Signal B.

Phase discriminator (Counter)
See count input

Phase tolerance
Deviation of the pulse-edge from Channel A to B, relative to the phase angle 90°.

Pilot signal
An output signal released before the main preset value is entered according to the setpilot signal value.

P.L.C.
Programmable Logic Controller: control system whose program is stored in a program memory and can be changed.

PNP input/output
Transistor input/output circuit implemented with a pnp transistor, and thus positive switching.

Position indicators
Processing of angular and path information, thus allowing position to be determined; no control outputs.

Power-up reset
See reset modes

Prescaler
The factor by which the incoming pulses in the counter are multiplied. Used when theincoming count pulse does not correspond to the desired display unit, e.g. length measurement with an existing roller mechanism and standard pulse generator.

Preset
For programmable absolute shaft encoders: The programmed numerical value is accepted as output value (output value = preset value).

Preset counter
Preset counters are counters with control functions, e.g. shutting down a machine after a certain number of pieces has been produced.

Preset value
Setting value (a set value); a signal is released when this value corresponds with the counted value.

Program reset
Count reset with simultaneous program reset.

Protection class
The enclosure class is designated according to DIN 40050, by IP and a two-figure code number.

1st digit	Degree of protection against ingress of solid bodies:
0	no special protection
1	solid bodies with dia. > 50 mm, no protection against intentional penetration
2	solid bodies with dia. > 12 mm, warding off fingers etc.
3	solid bodies with dia. > 2.5 mm, warding off tools, wires, etc. (thickness > 2.5 mm)
4	solid bodies with dia. > 1 mm, warding off tools, wires, etc. (thickness > 1 mm)
5	dust in harmful quantities, complete shock-hazard protection
6	dust (dust-tight), complete shock-hazard protection

2nd digit	Degree of protection against water
0	no special protection
1	water dripping vertically
2	water dripping at angles up to 15° from vertical
3	water dripping at angles up to 60° from vertical (spraying water)
4	water from all directions (splashing water)
5	water from a nozzle from all directions (hose-water)
6	heavy seas or strong jet of water (flooding)
7	water, if the device is immersed in water under specified conditions of pressure and time (immersion)
8	water, if the device is submerged constantly. The manufacturer must describe the conditions (submersion)

(For numbers 1 to 8, water must not penetrate in harmful quantities.)
Example: IP 65 A device thus designated is dust-tight, and protected against hose-water.

Protection class (Counter)
Designated with IP (international protection) and a 2-digit number according to DIN 40050
– 1st digit
Degree of protection against penetration by solid bodies:
0 no special protection provided
1 solid bodies of > 50 mm; no protection against intentional access
2 solid bodies of > 12 mm; fingers, etc. cannot be inserted
3 solid bodies of > 2.5 mm; tools, wires, etc. (thickness > 2.5 mm) cannot be inserted
4 solid bodies of > 1 mm; tools, wires, etc. (thickness > 1 mm) cannot be inserted
5 dust in harmful quantities; complete protection against contact
6 dust (dustproof); complete protection against contact
– 2nd digit
Degree of protection penetration by water
0 no special protection provided
1 water dripping vertically
2 water dripping up to 15° from the vertical
3 water dripping up to 60° from the vertical (spray)
4 water from all directions (splashing)
5 water jet projected from a nozzle, from all directions (jet spray)
6 heavy seas or powerful water jet (flooding)
7 immersion in water under a defined pressure and period of time (immersion)
8 submersion in water indefinitely. Conditions to be described by the manufacturer (submersion) (water shall not penetrate unit in critical amounts under conditions 1-8)
Example: IP54 A unit with this designation is protected against the penetration of dust in harmful quantities and against splashing water.

PSC
See prescaler

PTB approval (Counters)
Approval by the Physikalisch Technische Bundesanstalt (appropriateness for verification)

PTB approval
Approval for use by the Physikalisch-Technische Bundesanstalt, the German government materials testing institute.

Pulse frequency
See counting frequency

Pulse (repetition) frequency, max.
The maximum signal frequency achievable by the shaft encoder, the product of rotary speed and number of markings.

Pulse generation
– for electromechanical AC counters
An AC counter can be operated directly with mains voltage. Attention! If the counter coil lies parallel to a chain of contactors which are supplied by a common isolation transformer (VDE regulations), extremely high voltage peaks result which reach several kV capable of destroying the counter coil. In this case, we recommend operating the counter with 24 VAC via a separate transformer.
– for electromechanical DC counters fed by battery voltage up to 25 pulses

Pulse generator
Correct counting results depend to a large extent on the appropriate choice of pulse generator. In mechanical pulse generators, bounce contact of > 3 ms should not occur, as miscounts will otherwise be registered. For counting rates of up to 10 Hz, microswitches, limit switches, limit switches or cam-actuated sets of contact springs are suitable; for counting rates of up to 30 Hz, miniature relays can be used. The use of electronic pulse generators (proximity switches, light barriers, shaft encoders, etc.) is recommended for counting rates higher than 30 Hz.

Pulse scaler
A component which generates an output pulse after a specified number of input pulses. Used whenever the incoming count pulse does not correspond to the desired unit of display.

Pulse-weighting factor
See prescaler

Pulse width measurement
Time measurement; the duration of a pulse is registered and displayed when the pulse is ended until this value is updated.

PVC
Polyvinylchloride; plastic coating of device cable