It's possible to operate multi units synchronously.
The NCT08-02 contains 8 CH counters. You can use more than 9 channels at synchronous mode
using multi units of NCT08-02.
Here are procedures of this usage.
Connect the RUN signal(TTL OUT) of first unit to the GATE signal(TTL IN) port of second unit.
It's the same way to the third unit.
Send "DSAS" command to latter unit. The latter units don't stop counting automatically.
Send "START" command to latter unit. The latter units start counting action.
Depend on your usage, put on "GATE" signal to first unit.
Depend on your usage, preset timer stop command to first unit. ("CLTM","ENTS","STPRdddd")
Depend on your usage, preset counter stop command to first unit. ("CLPC","ENCS","SCPRdddd")
Activate count mode of first unit by the command "START".
This procedure activate more than one unit at the same timing chart.
(a) Regarding NCT08-02 when it receives data read command, it stops count and timer action for 120 ns.
This disable period is need to get latest data to latch 48 bits count data.
If you read out count data 100 times/ｓ, total disable period is 120ns × 100 = 12μｓ/s.
Disable period for each reading access is always same 120ns.
Counter and timer stops simultaneously you'd better to read data by minimum command.
When in counting pulse during "GATE" signal which comes from outside, you'll notice that counting period
is shorter than read out period.
Unless read out count values in counting period there is no error of measurement.
When in timer stop mode or counter stop mode, there is no dead time to read out count values.
(b) Notes when count multiple units at simultaneous control. (See ５．Synchronous operation by multi counter units.)
When you use multiple units at simultaneous control, you have to pay attention to error of measurement.
Concerning only read out module, measuring period is stopped for 120ns.
There for there are some errors of pulse count between units, because of the times or timing of data read out.
Example) When read out 100Times/1s for one module.
The period of counting pulse is １２μs shorter. １２０ns×１００＝１２μs.
In this case error ratio of count is １２μs／１s (0.00012%).
５．Synchronous drive of multi units
６．Regulations and guidelines
７．Interfacing to external devices
５Ｖ
TTL IC
GATE INPUT
GND
LEMO
TTL IC
START, STOP
GND
LEMO
GND
TTL LEVEL
(0～３．３Ｖ OR 5V)
TTL LEVEL
(0～３．３Ｖ OR 5V)
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