Identification Systems - Introduction

The following rule applies in general:If the object passes at about half the maximum read distance, the diagonal of the read head can be used as reading range for inductive systems if the code/data carrier has roughly the same diameter. In practice, the reading must still be correct if a read attempt fails, for example, due to EMC influ- ences. Thus, only half the maximum passing speed v
max

[s] time Read[m] range Readtsv

practice is recommend-ed for practical use. This was taken into account in the calculation exam-ples. The communication time depends on the system (see table). IDENT-I IDENT-I IDENT-M

system V

IDENT-M

system T system P system V

Frequency125 kHz250 kHz2.45 GHz2.45 GHz Read fixed code 40 ms 15 ms 1) 8 ms 2) 80 msRead n 4-byte blocks(n 30) + 100 msn 30 ms 1) 17 ms 2) 80 ms Write n 4-byte blocks (n 100) + 100 ms n 300 ms 1) 30 ms 2) 300 ms 1) If only one head is connected. Otherwise, the times are prolonged by the factor of the head number due to the multiplex function. 2) If "single" commands are used, the activation time of the antenna of approx.70ms must be taken into account. Calculation example 1 for system IP (125kHz): •Read/write head in F15 design (200 mm in the diagonal)•Data carrier with a diameter of 100 mmRead fixed code (t = 40 ms)v
practice = 0.2 m / (2 40) ms =2.5 m/sRead 4 bytes t = (1 30) +100 ms = 130 msv
practice = 0.2 m / (2 130) ms =0.7 m/sRead 5 bytes
As reading can only be performed in 4-byte blocks, 2 4 byte blocks must be read, of which 5 bytes are transmitted to the control. t = (2 30) +100 ms = 160 msv
practice = 0.2 m / (2 160) ms =0.625 m/s
Note: If e.g. 6 bytes are read, but the beginning and the end do not correspond to the 4-byte blocks, 3 x 4-byte blocks must be read and the time is increased by another 30ms. If the data is to be available quickly and selectively, it is recommendable to always start the information with the beginning of a 4-byte block and leave some bytes in between unused, if necessary. Calculation example 2 for system IV (250kHz): •Read/write head in FP design (~110 mm in the diagonal)•Data carrier with a diameter of 50 mmRead fixed code t = 15 ms number of connected headsv
practice = 110 mm / (2 15) ms =3.67 m/s (one head)Read 2 bytes t = (1 30) msv
practice = 110 mm / (2 30) ms =1.83 m/s (one head)
Issue date 2005-08-18 - Catalogue Identification Systems 2005/2006

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