Omron V670 Series, User Manual

Page: 36 / 143

2-5 Communication Range Specifications
2-18
In the communication with a tag, any data is read and written at every 4 bytes. Therefore, to minimize the communication time, specify
the address and the number of bytes suitably so that the address for writing can be a multiple of 4.
Example: If 4 bytes of data is written from the address 0001h, change the address to 0000h.
If you cannot change as stated above due to the structure of change system, add the following time to the communication time.
♦ TAT
Time from the start of command transmission by a host device to the end of receiving of response to the host device. It can be calculated
from the communication time and the number of characters of command/response. The formula is as follows:
TAT = command transfer time + communication time + response transmission time
* The number of bits per character and baud rate vary depending on the communication conditions (baud rate, data length, parity and
stop bit).
Assuming that the number of characters of command is A, the number of characters of response is B, the baud rate is 9600 bps, data
length is 7 bits, parity is even and stop bit is 2 bits, the following formula can be obtained:
When a protect function is used +2.9 ms
When a start address is not a multiple of 4 +2.9 ms
When an end address (start a the number of addresses) is not a multiple of 4 +2.9 ms
Correct Usage
The formula above calculates the time when processing (transmission of command) starts if the ID tag is within an area
of communication with an antenna. The time varies depending on a communication mode and ID tag status.
Bits per character (bit)
Baud rate (bps)
Transmission time = × number of characters (second)
11 × (A + B)
9600
TAT =
+ communication time (second)