Frequency, Rate & Period Meter

With dual, independently field-scalable channels

dFrequency meter by TD Micronic


  • Two independently field-scalable channels A & B for frequency, rate or total
  • Inputs from NPN or PNP proximity switches, contact closures, digital logic, magnetic pickups down to 12 mV, or AC inputs up to 250 Vac
  • Frequencies from 0.005 Hz to 1 MHz
  • Line frequency measurement to 60.0000 in a few line cycles
  • Universal 85-264 Vac / 90-300 Vdc or 10-48 Vdc / 12-32 Vac power
  • Transducer excitation output (isolated)
  • Wide choice of options:
    - 2 or 4 relays, mechanical or solid state (isolated)
    - 1 or 2 analog outputs (isolated)
    - Serial data I/O: Ethernet, USB, RS485, RS232 (isolated)
    - Rate and total simultaneously, custom curve linearization, arithmetic
      functions A+B, A-B, AxB, A/B, A/B-1 (draw)
frequency meter

The Standard counter provides commonly used basic capabilities:

  • The dual-channel frequency, rate and period meter is a basic operating mode of the counter with the FR signal conditioner board. It can display frequency from 0.005 Hz to 1 MHz, rate in engineering units, and period (inverse of frequency). The normal displayed value can range up to 999,999 counts. Above that level, the display will flash and go into four-digit XXXXEX scientific notation. Each channel (A or B) may be independently scaled for frequency, rate or period. The displayed channel is selected via a front panel pushbutton. Examples of applications are the accurate display of AC line frequency, RPM, speed from proximity switch inputs, and flow from turbine flow meter inputs.
  • Fast, high resolution measurements. The counter determines frequency by timing an integral number of periods over a specified gate time, and then taking the inverse of period. Rate is obtained by multiplying the input by a scale factor. The inverse period approach allows greater accuracy and faster update times than conventional meters which count signal pulses over a time interval. AC line frequency may be accurately measured to 50.0000 or 60.0000 Hz in a few line cycles. 1000 Hz signals may be measured to 0.01 Hz resolution at up to 25 readings per second. Fast response is ideal for alarm and control applications.
  • For noise reduction, a count by 10 or 100 feature with rounding is selectable. Variations in the displayed reading can also be reduced by selecting a longer gate time. An adaptive digital filter is selectable to reduce variations due to noise while rapidly responding to actual changes in the signal.

An Extended counter version provides all capabilities of the Standard counter plus the following:

  • Rate and total simultaneously. One channel can display total while the other displays rate. The selection for either channel is via a front panel pushbutton. This mode is ideal for flow applications when the same signal is applied to both channels.
  • Custom curve linearization. Exceptionally accurate custom curve linearization allows linearization of the low end of turbine flowmeters. For setup, up to 180 data points can be input into a spreadsheet or text file by the user. The computer then calculates nonlinear segments, which are downloaded into the meter via RS232. The Extended version allows linearized rates to be totalized.
  • Arithmetic functions. The Extended counter makes arithmetic functions available, namely A+B, A-B, AxB, A/B and A/B-1 (draw). For example, A+B allows two input flows to be summed for total flow, while A-B allows outflow to be subtracted from inflow for net flow. If transducers with a frequency output are used, AxB allows horsepower to be displayed based measured torque and RPM, or based on force and velocity. A/B can be used for the proper mixing of ingredients, while A/B-1 (draw) is used to compare rates for stretching or tensioning.

Signal conditioner board for TDM Frequency, Rate and Period MeterThe FR dual-channel signal conditioner accepts inputs from proximity switches with a PNP or NPN output, TTL or CMOS logic, magnetic pickups, contact closures, low-level outputs from turbine flow meters down to 12 mV, and high-level AC line inputs up to 250 Vac. A built-in isolated 5, 10, or 24 Vdc excitation supply can power proximity switches and other sensors, thus eliminating the need for an external power supply.

Designed for system use. Optional plug-in boards for communications and control include Ethernet and other serial communication boards, dual or quad relay boards, and single or dual isolated analog output boards. s may be powered from 85-264 Vac or optionally from 12-32 Vac or 10-48 Vdc. The display is available with red or green LEDs. The 1/8 DIN case meets NEMA 4X (IP65) specifications from the front when panel mounted. Any setup functions and front panel keys can be locked out for simplified usage and security. All power and signal connections are via UL / VDE / CSA rated screw clamp plugs.

Readout 6 LED digits, 7-segment, 14.2 mm (.56"), red or green.
Display Range -999999 to +999999, XXXXEX notation beyond 999999
Zero Adjust -999999 to +999999
Span Adjust 0 to 999999
Indicators Four LED lamps
Types AC, pulses from NPN, PNP transistors, contact closures, magnetic pickups.
Signal Ground Common ground for channels A & B
Channel A Freq. 0.005 Hz to 1 MHz
Channel B Freq. 0.005 Hz to 250 kHz
Minimum Signal Nine ranges from (-12 to +12 mV) to (+1.25 to +2.1V).
Maximum Signal 250 Vac
Noise Filter 1 MHz, 30 kHz, 250 Hz (selectable)
Contact Debounce 0, 3, 50 ms (selectable)
Update Rate
Freq. Technique Inverse period
Conversion Time Gate time + 30 ms+ 0-2 signal periods
Gate Time Selectable 10 ms to 199.99 s
Time Before Zero Out Selectable 10 ms to 199.99 s
Time Base Crystal calibrated to ±2 ppm
Span tempco ± 1 ppm/°C (typ)
Long-term Drift ± 5 ppm/year
Voltage, standard 85-264 Vac or 90-300 Vdc
Voltage, optional 12-32 Vac or 10-48 Vdc
Frequency DC or 47-63 Hz
Power  consumption (typical, base meter) 1.2W @ 120 Vac, 1.5W @ 240 Vac, 1.3W @ 10 Vdc, 1.4W @ 20 Vdc, 1.55W @ 30 Vdc, 1.8W @ 40 Vdc, 2.15W @ 48 Vdc
Power Isolation 250V rms working, 2.3 kV rms per 1 min test
Excitation Output (standard)
5 Vdc 5 Vdc ± 5%, 100 mA
10 Vdc 10 Vdc ± 5%, 120 mA
24 Vdc 24 Vdc ± 5%, 50 mA
Output Isolation 50 Vdc to meter ground
Analog Output (optional)
Output levels 4-20 mA, 0-20 mA, 0-10V, -10 to +10V (single-output option)
4-20 mA, 0-20 mA, 0-10V (dual-output option)
Current compliance 2 mA at 10V ( > 5 kΩ load)
Voltage compliance 12V at 20 mA (< 600Ω load)
Scaling Zero and full scale adjustable from -99999 to +99999
Resolution 16 bits (0.0015% of full scale)
Isolation 250V rms working, 2.3 kV rms per 1 min test
(dual analog outputs share the same ground)
Relay types 2 Form C contact relays or 4 Form A contact relays (NO) 2 or 4 Form A, AC/DC solid state relays (NO)
Current Ratings 8A at 250 Vac or 24 Vdc for contact relays 120 mA at 140 Vac or 180 Vdc for solid state relays
Output common Isolated commons for dual relays or each pair of quad relays
Isolation 250V rms working, 2.3 kV rms per 1 min tes
Serial Data I/O (optional)
Board selections RS232, RS485 (dual RJ11 or RJ45 connectors), USB, Ethernet, USB-to-RS485 converter, Ethernet-to-RS485 converter
Protocols Modbus RTU, Modbus ASCII, Modbus TCP (Ethernet), TDM ASCII
Data rates 300 to 19200 baud
Digital addresses 247 (Modbus), 31 (TDM ASCII),
Isolation 250V rms working, 2.3 kV rms per 1 min test
Operating temperature 0°C to 55°C
Storage temperature. -40°C to 85°C
Relative humidity 95% at 40°C, non-condensing
Protection NEMA-4X (IP-65) when panel mounted
Electrical Connections
Signal pinout of TDM frequency, rate and period meter
AC Line Frequency
AC Line Frequency Meter The will accept line voltages up to 250 Vac and display line frequency to 6-digit accuracy (50.0000 or 60.0000) in a few line cycles. Fast low frequency response is achieved by timing the period and taking its inverse.
RPM and Speed
Tachometer and Pulse Input Rate Meter The can sense the low-level signals from magnetic pickups or the NPN or PNP transistor output of active sensors. These can be powered directly by the meter. Display in RPM or units of speed is achieved by mathematically scaling the meter.
Flow Rate and Simultaneous Total
Simultaneous Rate Meter and Totalizer The is compatible with all flow meters which generate pulses at a frequency proportional to flow rate. The Extended version can display scaled rate or total for the same input at the push of a button, and alarm from both the rate and total. The Extended version can also linearize flow transducers so as to extend their dynamic range.
Arithmetic Combinations of Two Channels
Dual Pulse Input Rate Meter to Combine Two Rates The Extended offers A+B, A-B and A/B arithmetic functions. A+B allows two input flows to be summed for total flow, while A-B allows outflow to be subtracted from inflow for net flow. Flow ratios aid in the proper mixing of ingredients
Custom Curve Linearization
Custom Curve Linearization for  Rate Meters The Extended can linearize the output turbine flow meters, which tend to be nonlinear on the low end. Linearizing improves the dynamic range and accuracy of turbine flow meters.
System-level Capabilities
The dual channel rate meter can independently scale, display and alarm two pulse input channels. All signal or alarm data can further be transmitted via RS232 or RS485, including peak readings and arithmetic combinations of the two rates. The displayed rates can also be transmitted as an isolated 4-20 mA or 0-10V analog output. System Interfaces of  Frequency Meters and Rate Meters

Request More Info: