Intermec Trakker Antares 2460, Руководство пользователя

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TRAKKER Antares 246X Stationary Terminal User’s Manual nugget
39
4-8
•
LRC
•
Poll (Polling) (enabled or disabled)
•
SOM (Start of Message)
•
Timeout Delay
Configurable protocol uses EOM to determine the serial communications mode. When
EOM is disabled, the terminal communicates in Character mode. When EOM is
enabled, the terminal communicates in Frame mode.
After you enable EOM, you can set a value for these serial port parameters:
•
Configuration commands via serial port
•
Handshake
•
LRC
•
SOM
After you enable Handshake, you can set a value for poll and the timeout delay.
Master Polling Protocol
Master Polling Mode D protocol requires the 246X terminal to ask the downline serial
device for data it may have (polling) and to request to send data to the serial device
(selecting). There is no automatic polling, so your application must poll periodically for
data.
Before each transmit operation, the terminal issues the SEL sequence for the device
addressed and sends the data if an acknowledge is received. Before each receive
operation, the terminal issues a poll sequence and waits for data or the RES character
(no data is available to send ).
Baud rate is the only serial port parameter you can define for Master Polling protocol.
Multi-Drop Protocol
Multi-drop uses protocol sequences similar to Polling Mode D with the extension of
device addressing, which allows up to 32 devices on one 4-wire RS-485 line.
Multi-Drop protocol is typically used in CrossBar networks. Due to timeout parameters,
the baud rate must be 2400 or higher. Multi-Drop protocol is only available for the
2460 (COM2).
When you configure COM2 for Multi-Drop protocol, the serial port is automatically
configured to communicate via RS-422/485.
Here are the serial port parameters you can define:
•
Baud rate
•
Multi-drop device address