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DPC31 HW

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DPC31 HW Description

Version V1.0 Page 53

7.5.1.3 Interface Signals

Pin Name Signal Name Input=I

Output=O

Comment

TXD_TXS

RXD_RXS

RTS_TXE

XCTS_RXA

TxD

RxD

RTS

XCTS

Send Data

Receive Data

Enable of the send drivers

Sender Enable

Figure 7.5-1:

Asynchronous PROFIBUS Interface of the DPC31

In the test mode, all outputs are switched to high resistance.

7.5.2 Synchronous Physics Unit (Manchester)

The synchronous interface makes data transmission according to IEC 1158-2 possible. It includes services

of the interface -defined in this standard- between the following: data link layer and physical layer (

(FDL Ph

layer interface)

, the sublayers Ph DIS

(DCE independent sublayer)

and Ph MDS

(medium dependent

sublayer)

for wire media and the corresponding

MDS-MAU interface

. In addition, the

station management

physical layer interface

is implemented (parts of the service primitives, optionally defined in Standard IEC

1158-2). The so-called “medium access unit (MAU)” is not implemented, which includes the following: the

initial pulse shaper, the line driver, the receive amplifier, the receive filters and the line coupling (if needed,

with remote supply setup). The MAU can be set up with little effort with the SIM1 Analog ASIC.

Receive

Filter

Tx-Control/

FCS-Generator

Tx-Register/

Tx-Buffer

Rx-Register/

Rx-Buffer

Manchester

Encoder/

Delimiter

Generator

S/R_Unit

Rx-Control/

FCS-Check

Clock

Recovery

Manchester

Decoder/

Delimiter

Detector

TxS,

RTS/ADD

RxS

Transmitter

Receiver

Gap-Timer

Figure 7.5-2:

Block Diagram of the Synchronous Interface.

7.5.2.1 Transmitter

The transmitter converts the parallel data structure into a serial data stream. The synchronous transmission

procedure according to IEC 1158-2 processes with Manchester coding and start and end delimiters. Each

message is preceded by a preamble. The length of the preamble is stored in the preamble register (refer to

3.3).

In contrast to the asynchronous interface, the most significant data bit is transmitted first

. The

transmitter generates a 16-bit CRC field and attaches it to the data field.

according to IEC 1158-2, Chapter 7.

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