W-Ack - Leuze electronic MA 204i Technical Description

Modular interfacing unit for leuze ident and rs 232 devices on profibus dp

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If the buffer still contains more data ("DEX bit = 1), the next remaining user data present in

the buffer is transmitted by toggling the "R-ACK" control bit. This process is to be repeated

until the "DEX" bit returns to "0"; all data has then been removed from the buffer. "R-ACK"

must be toggled here again once more as a terminating read confirmation in order to release

data transmission for the next read cycle.

Used status and control bits:

• DLC

• BLR

• DEX

• R-ACK

Writing slave data in Collective mode (PLC -> gateway)

The data sent by the master to the slave is first collected in a "transmit buffer" by setting

the "CTB" bit (Copy to transmit buffer). Please observe that data provided is transmitted

directly by toggling the bit.

The data is then sent in the order received from the buffer to the connected Leuze device

via the serial interface with the command: "SFB" (Send data from transmit buffer). Please

don't forget the suitable data frame!

Afterward, the buffer is again empty and can be written with new data.

Notice!

With this function, it is possible to temporarily store longer data strings in the gateway

independent of how many bytes the used fieldbus can transmit at once. With this function,

longer PT sequences or RFID write sequences, for example, can be transmitted, since the

connected devices can, in this way, receive their commands (e.g., PT or W) in a continuous

string. The respective frame (STX CR LF) is needed to differentiate between the individual

telegrams.

Used status and control bits:

• CTB

• SFB

11.1.2

W-ACK

If PLC data is provided and transferred without a state change of the CTB bit, it goes directly

to the RS 232 interface with the set telegram data length. Incomplete (incl. data frame) or

faulty telegrams can cause error messages in the connected device!

Examples for the activation of a Leuze device

In the data part (starting at byte 2) of the telegram to the gateway, a "+" (ASCII) is sent for

activation.

Leuze electronic

204i

Modes

Writing in blocks

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