Hitachi EH-150 - Page 125

Appendix A Response performance
A-2
[ Rough estimate of response time ]
Calculate the rough estimate value of the response time of the ASR communocation by the following.
Response time : 30ms * T
T : Count of internal processing
- Calculation method of T : T = T
SW
+ T
SB
+ T
R
(1) Send area
The count of internal processing is calculated by each item on both word and bit.
- Word data T
SW
: (Number of send data) / 120 ( It rounds up below the decimal point )
(Example) Number of send data = 200 words : T = 2 (200÷120)
- Bit data T
SB
: (Number of send data) / 240 ( It rounds up below the decimal point )
(Example) Number of send data =200 bits : T=1 (200÷240)
(2) Receive area
At 1 connection : T
R
: (Number of receive data)÷100 ( It rounds up below the decimal point )
(Example) Number of receive data = 120words : T=2 (120÷100)
［ Example of response time］
The response performance of the ASR I/O area setting in table A.3 is shown below.
- Send time of word data
T
SW
= (200÷120) + (200÷120) + (200÷120) + (200÷120) + (200÷120)
= 2 + 2 + 2 + 2 + 2
= 10
- Send time of bit data
T
SB
= (1÷240) + (1÷240) + (1÷240) + (1÷240) + (1÷240) + (1÷240) + (1÷240) + (1÷240)
= 1 + 1 + 1 + 1 + 1 + 1 + 1 + 1
= 8
- Receive time
T
R
= (200÷100) + (200÷100) +(200÷100) +(200÷100) +(200÷100) +(200÷100)
= 2 + 2 + 2 + 2 + 2 + 2
= 12
T== T
SW
+ T
SB
+ T
R
= 10 + 8 + 12 = 30
Response time = 30ms * T = 30ms * 30 = 900ms
Therefore, response time becomes 900ms.
*) Set the ASR I/O area so that the response time may become within about 80% at a cyclic time at a cyclic
transmission.
Table A.3 ASR I/O area setting
Connection No. 1 2 3 4 5 6
Number of receive data 200 words 200 words 200 words 200 words 200 words 200 words
Item No.1 1 bits 200 words 200 words 200 words 200 words 200 words
Item No.2 1 bits
Item No.3 1 bits
Item No.4 1 bits
Item No.5 1 bits
Item No.6 1 bits
Item No.7 1 bits
Item No.8 1 bits
Item No.9
Number of send data
Item No.10
Note: The column of the blank in the table is set no data.