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TDP-3921-R Periomatic Tachometer
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A special tachometer, TDP-3921-R, is the first choice of Japanese car industry due to its unique functions. It offers two channels photo MOS relays output and RS-232C high-speed communication. Above all, it has unique optional functions like BCD and analog output with an ideal response time of 1ms.Its measurement range is from 0.0006Hz to 100kHz with a programmable display to read out in terms of wide range of units like rpm, rps, Hz, km/h, l/min, g/h, etc.

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High speed analog output
  The measured value can be transmitted as -10 to 10V analog signal (0 to 10V when input is single phase pulse) to other devices / system such as data logger or PLC. The polarity of analog output follows the direction of rotation of pulse generator. The analog signal can be scaled, e.g. 0 to 10V = 0 to 8000rpm. Where as the updating time is 1ms.

Wide range


Input frequency range is 0.0006Hz to 100kHz without any change in range. The display accuracy is 20ppm±1digit.

Employing PERIOMATICTM technology


The forecast computation PERIOMATICTM, versatile software, is the principle of working of TDP-3921-R. It enables the user to get analog output voltage even in the presence of heavy fluctuations. The PERIOMATICTM has stop (zero speed) forecasting function, so the TDP-3921-R immediately responds to sudden stop of the incoming pulses.

Compatibility to variety of Inputs
  The TDP-3921-R can directly be connected to varying sensors like AC magnetic pickups, rotary encoders, proximity sensors, and pulse output devices. The TDP-3921-R can detect the direction of rotation of pulse generators and indicate it by minus or plus sign on LED display and analog output when 2 phase signals are applied.
Large 14.2mm bright LED display with fixed or floating decimal point
Three kinds of averaging function, time average, moving average, and pulse dividing average are used to dealt with irregular and heavily laden with fluctuation incoming pulses.
It offers independent and programmable updating times of display and analog output

Name Periomatic tachometer
Model TDP-3921-R
Measurement PERIOMATICTM processing
Number of inputs 1
Input frequency range 0.0006Hz-100kHz
Resolution 102ns (9.8MHz)
Input method 1)Single phase pulse
2)UP/DOWN signals of 2 inputs (separate pulse)
3)2 phases A and B with 90degreephase difference
Input pulse width MIn.4micros (both H level and L level)
Input lovel Logic : logic signals of more than 3.5V in H level and less than 1V in L level
Zerocross : alternative signal between plus or minus100mV to plus or minus30V
Withstand voltage plus or minus30V
Input connector Terminal block (7.62mm intervals, M3 terminal screw)
Sensor power supply +12V 50mA max
Measurement mode Frequency meter mode / Period meter mode
Operation rate Setting the displayed value against input frequency
Input frequency rate : 0.00001-999999 (Hz)
Display rate : 0.00001-999999
Dividing rate (pulse average) 1-999 (divided frequency by software)
Number of moving average 1-8
Dynamic forecastTM 8 steps
(continuous estimate and, one cycle maintaining are included)
Chatter suppressing function The chattering is removed
Dual range Setting two kinds of operation rate
Memory of the set value INonvolatile memory (EEPROM)
Displayed colors Red LED
Display 7 segments of LEDs, character height is 0.56" inches (14.2mm)
Display digits 6 digits
Range of display -199999-999999
Display of polarity -means lighting, +means no lighting
Over display By the OL display
Zero display Reading of zero suppression
Position of decimal point Automatic range and fixed range
□□□□□□.- □.□□□□□ 
Display update time 0.1-99.9s
Display accuracy 20ppm plus or minus1 digit @23degree Celsius
【Analog Output】
Output voltage range 10V
Resolution About 10000 (-10V - +10V)
Output updating time 0.001-99.99s
Full scale setting range Display value setting in full scale (0.00000-99999)
Load resistance Min. 4.7kohm
Output accuracy Max. plus or minus0.2% of full scale @23degree Celsius
Temperature fluctuation Max.200ppm/
Linearity Max. plus or minus0.1%
【Comparator Output】
Number of channels 2 channels (HIGH and LOW)
Output signal Isolated noncontact output (photo moss relay)
Rating DC 350V maximum 80mA (resistance load)
AC240V maximum 80mA (resistance load)
ON resistance Under 50ohm
Updating time Synchronization is selected for display updating time and analog output updating time
Response time Max. 3ms
Output connector Terminal block (7.62mm intervals, M3 terminal screw)
Communication method Asynchronous commmunication method
Communication level Serial communications by RS-232C
Communication parameter Fixed at baud rate of 2400bps
Communication connector Hexpole plug-in phone jack
Output timing Communication output of displayed data at every display updating
Power supply input
*factory delivery option)
TDP-3921-RA10 AC100V 10% 50/60Hz
TDP-3921-RA11 AC115V 10% 50/60Hz
TDP-3921-RA20 AC200V 10% 50/60Hz
TDP-3921-RA23 AC230V 10% 50/60Hz
TDP-3921-RDF DC9.6-30V
Electric power consumption Max. 8VA
Outside dimentions 96 (W) × 48 (H) × 150 (D) mm DIN standards
Weight Approximately 700g
Operating temperature & humidity limits 0 to +40 / Under 85%RH (no dewing)
Storage temperature -20 to +70


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