Tektronix FCA3100 Series, FCA3000 Series How-to Manual

How-To Guide Continuous Measurements with Zero Dead-time

Continuous Measurements with Zero Dead-time

FCA3100 Series

How-To Guide

How-To Guide Continuous Measurements with Zero Dead-time

Tektronix FCA3100 Series Timer/Counter/Analyzer introduces the concept of Continuous Data
Output with Zero Dead-time. While this How-to Guide will focus on continuous measurement for
the FCA3100 series products, it will also describe the basic functionality of measuring and
streaming data and the differences of this between the FCA3000 and FCA3100 Series products.

1. The FCA3000/FCA3100 Measuring and Output Data Transfer Modes

Let’s begin with a summary of the different measurement and output data transfer modes in the FCA3000
and FCA3100 series products.

The FCA3000 and FCA3100 Series products can operate in several different measuring and data transfer
modes:

 Single (individual) measurements
 Block measurements

Mode Local Operation Remote Operation

 Zero-dead-time block measurements
 Zero-dead-time single measurements

(FCA3100 series only)

Single
measurements
(with dead-time)

Block
measurements
(with dead-time)

Zero-dead-time
single
measurements

Zero-dead-time
block
measurements

Mode Max speed (calculated results/second)

FCA3100 FCA3000

Single measurements
(with dead-time)

FCA3100 FCA3000 FCA3100 FCA3000

Values mode Values mode READ?. INIT+FETCH?

GET INIT +TALK ONLY

Analyze mode of
any measurement

Freq BtB,
Period BtB, TIE

Freq BtB,
Period BtB,
TIE &
Analyze mode

Analyze mode of
any measurement

Not available READ?. INIT+FETCH?

Not available READ:ARR?

GET: 650/s TALK ONLY: 4000/s GET: 500/s

READ:ARR?
INIT/FETCh:ARRay?

GET INIT +TALK ONLY

INIT+FETCh:ARRay? of
Freq BtB, Period BtB, TIE
(1-timestamp/value);
Or Raw timestamp
(4-timestamp/value)

READ?.
INIT/FETCH? GET

READ ARR?
INIT/FETCH ARR?

Not available

READ ARR?
INIT/FETCH ARR? of
Raw timestamp
(4-timestamp/value)

Block measurements
(with dead-time)

Zero-dead-time
block measurements with dead­time between blocks

Continuous zero-dead-time
block measurements

READ:ARR?: 15K Sa/s READ ARR? 5K Sa/s

READ:ARR?: 15K Sa/s, 250K Sa/s
to internal memory of 3.75MB

ARM:COUNT INF
READ:ARRay:? 10K Sa/s

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READ:ARR?: 15K Sa/s, 250K Sa/s
to internal memory of 750KB

Not available

How-To Guide Continuous Measurements with Zero Dead-time

Single Measurements

 READ?
 INIT+FETCH?
 GET

Single measurements mean that you do one measurement at a time and transfer to the display and to the
data outputs (GPIB or USB). This mode has a dead time between measurements of approx. 2 ms, when you
trigger the counter’s individual measurements, one by one, via the GET command (Group Execute Trigger),
from the connected controller. The internal measurement memory buffer is not involved in this mode.

Using the above commands single measurements, you can control exactly when you want to initialize (start)
the measurement. The communication process is simplified:

 Controller talker /FCA3000 or FCA3100 listener: “start measurement” (GET)
 Controller talker / FCA3000 or FCA3100 listener: “send result” (FETCH?)
 FCA3000 or FCA3100 talker/ Controller listener: “sending result data”
 Controller talker / FCA3000 or FCA3100 listener: “start next measurement” (GET) …

FCA3100: In addition to the FCA3000 modes, the FCA3100 has an additional output mode;
Talker only (SYSTem:TALKonly ON)

Talker only differs from the GET-triggered individual measurements in that the counter will be triggered once
and after that the counter will output measurement data at the highest possible rate, without waiting for
subsequent trigger commands (GET) from the controller. This reduces the transfer overhead since the
controller is not taking control between the measurements. The controller cannot initialize individual
measurements and the measurement data continues to be sent until the controller stops the transfer via the
Interface Clear command or by pressing the ESC key on the counters front panel.

The dead-time between measurements in this “real-time” transfer mode is <250 microseconds. To reach this
throughput rate, the communication process is simplified:

 Controller talker /FCA3000 listener: “go to Talker only mode and start measurement”
 FCA3000 talker/ Controller listener: “sending result data”
 FCA3000 talker/ Controller listener: “sending result data”
 Etc…

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