MCC MIIC-203 Betriebsanweisung PDF herunterladen (Seite 27)

Use the I

C Message Editor to:

1. Set I

C Address.

The I

C Address is the I

C slave address of the slave device being addressed

on the bus. All slave addresses are displayed as even numbers (00...FE),

representing the 7 most significant bits of the 8-bit slave address transmitted

on the bus (aaaa aaa0).

The I

C adapter automatically supplies the 8

, least significant, Read/Write bit

when it sends the slave address across the bus. For master write operations,

the Read/Write bit is always transmitted as a logical 0 (aaaa aaa0). For master

read operations, the Read/Write bit is always transmitted as a logical 1 (aaaa

aaa1).

Use the I

C Address control to set the slave address of the slave device you

want to address on the bus.

2. Set Message Read/Write Direction.

As a bus master device, the I

C adapter can write data to, or read data from,

any device on the bus. Use the Msg Direction control to specify if the current

message is a master write, or master read, operation. Upon making your

selection, additional Write or Read parameters appear.

3. Specify Repeated Start Messages.

C Bus communications support an operation called Repeated Start. In this

operation, a message is sent across the bus beginning with a Start Condition,

but without a Stop Condition at the end of the message. The next message sent

across the bus begins with a Start Condition, in this case a Repeated Start.

An I

C Bus master, that successfully sends a message on the bus, owns the bus

until that master sends a message with a terminating Stop Condition. The

Repeated Start operation allows the bus master to retain control of the bus

while sending one or more messages on the bus. This prevents other bus

masters, in a multi-master system, from accessing the bus and interfering with

message sequences.

The Message Center supports Repeated Starts with the doStop control.

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MCC MIIC-203 Betriebsanweisung Seite 27