Datalogic Star Bedienungsanleitung PDF herunterladen (Seite 47)

REFERENCES

Case 4 – STARModem™ in Stand Alone Mode as Server (for an intelligent

printer)

Figure 4 – Stand Alone Mode with STARModem™ 2 Server

The two STARModems™ in this case can be configured in Stand Alone Mode,

however this limits one to be the dedicated Client and the other to be the dedicated

Server. Bi-directional communication is not possible in Stand Alone modes.

Assuming that Host 1 is Client we can analyze the following transmission parameters

from both STARModem™ 1 and STARModem™ 2’s point of view :

Modem 1 Client

Transmission Mode = 2 way

ACK/NACK from Remote Host = enabled

FIFO = enabled

Handshaking = any

The Client, (Host 1) sends a message to the Remote Host (Printer) and expects

an answer from the Printer. If the answer doesn’t arrive before Radio Protocol

Timeout, Modem 1 sends NACK to the Local Host.

• If Modem 2 Server

ACK/NACK Protocol = enabled as ACK/NACK

When STARModem™ 2 receives a new message, it sends it to the Printer.

The Printer answers with ACK. If Modem 2 acknowledges within the Radio

Protocol Timeout, Modem 1 sends an Empty Answer to its Local Host (Host 1),

otherwise it sends NACK.

• If Modem 2 Server

ACK/NACK Protocol = enabled as DATA/NACK

When STARModem™ 2 receives a new message, it sends it to the Printer.

The Printer answers with DATA (a string of up to 238 characters). If Modem 2

sends this DATA answer within the Radio Protocol Timeout, Modem 1 sends it to

its local Host (Host 1), otherwise Modem 1 sends NACK.

HOST 1

Printe

Modem 1

Modem 2

Client

Serve

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Datalogic Star Bedienungsanleitung Seite 47