Sentek LMC-J-0040-1 Manuel d'utilisateur télécharger pdf (Page 23)

IMJ00503 V3E.DOC Page 23 of 40 19.02.2009

4.6 SSI Interface

Parameter settings for SSI interface operation can be made via the Profibus.

Default state set on initial product delivery: DT Mode.

The LMC J 0050 3 has a SSI data interface (SSI = synchronous serial interface).

At the request of a SSI clock generator, the LMCJ0050 3 triggers a distance measurement

cycle, sending the data bit by bit to a controller for processing in the same order as it arrives at

the shift register. This process occurs in the measuring mode that was most recently stored in

the LMC J 0050 3. A desired measuring mode can be selected via the Profibus.

Transfer rates from 50 kHz to 1 MHz are available for selection. Selections should always take

into account the actual cable length.

The SSI interface works independently of the Profibus interface. It provides a data length of 24

bits and uses Gray code.

The pause interval between two bit sequences is 200 sec. All interface inputs are electrically

isolated. They provide an isolation strength of 500 V. To guarantee undisturbed data

transmission, screened twisted pair cables have to be used. This requirement is met by the

cable type which you can find quoted in the optional accessories section above (® Scope of

Delivery).

The following table shows selectable clock rates with corresponding cable lengths that must not

be exceeded:

Clock rate [kHz] Cable length [m]

< 500 < 25

< 400 < 50

< 300 < 100

< 200 < 200

< 100 < 400

1 2 ... 18 19 20 21 22 23 24 25 26 27 28 ... 38 39

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Sentek LMC-J-0040-1 Manuel d'utilisateur Page 23