Yokogawa PC-Based MX100 - Manual (Page 1240)

App-19
IM MX190-01E
Appendix
App
Appendix 3 Calculation of the MX100 Timeout
Value
The timeout value is the time until the saving of the data sampled at the
measurement interval to the CF card is started when the connection is cut off. It is
an integer greater than or equal to 60. The unit is seconds. The default value is 60 s.
To save the sampled data to the CF card without dropouts when the communication
is cut off, the data must be saved to the CF card before the unsaved data in the
FIFO buffer is overwritten. If the value is not appropriate, an error will occur when
saving to the CF card starts, and the sampled data will not be saved.
Refer to the calculation method of the timeout value shown below.
Timeout value (s) < (FIFO buffer size/data size per second) -20 s
FIFO buffer size = 2 MB (2097152 bytes)
FIFO data size per second = (the byte size of time + the byte size of the
measured value × the number of channels) × the number of measurements in 1
second
The byte size of time = 16 bytes
The byte size of the measured value = 4 bytes
20 s: Time required to save the data to the CF card (estimate)
Calculation Example 1
FIFO: 60 channels and scan interval of 10 ms
Data size per second = (16 + 4 × 60 ch) × 1000/10 = 25600 bytes
Setting = (2 MB/25600 bytes) - 20 s = 61.9 > 60 s (estimated setting)
Calculation Example 2
When three FIFOs below are running
FIFO: 40 channels and scan interval of 10 ms, 4 channels and scan interval of 50
ms, and 10 channels and scan interval of 100 ms
Data size per second = (16 + 4 × 40 ch) × 1000/10 = 17600 bytes
Data size per second = (16 + 4 × 4 ch) × 1000/50 = 640 bytes
Data size per second = (16 + 4 × 10 ch) × 1000/100 = 560 bytes
Setting = (2 MB/(17600 + 640 + 560 bytes)) - 20 s = 91.5 > 90 s (estimated setting)