Vanguard 3000 Multicarrier Cellular Data Modem & IP Router PN 134732-VG3000 Rev. D| Page 107
The manager is able to send I/O responses, alarms, and indications to a manager IP address via:
(a)
TCP (connection initiated by the Vanguard 3000).
(b)
UDP
A single operator-configurable transport service (UDP or TCP) is available at any moment and is used for both
directions (manager → Vanguard 3000; manager ← Vanguard 3000).
Congestion Control
Messages are not queued up. If the Vanguard 3000 cannot deliver them (for example, configured for TCP but no socket
opened), they are silently dropped.
Congestion Control for established TCP-based connections follow and are limited to the built-in Vanguard 3000 TCP/IP
stack congestion control mechanisms.
PDU Format
Vanguard 3000 I/O requests and responses, alarms/indications, and ACKs use existing NME 0183 (v2.30) sentences.
Frame format is as described in the following section.
The “II” (Integrated Instrumentation) NMEA talker mnemonic is used.
Protocol Exchanges
Read Vanguard 3000 I/O value
(1) manager requests value (NMEA msg: ACK)
(2) Vanguard 3000 responds with requested data (NMEA msg: XDR)
[manager application] ---(1)--- request ----------> [Vanguard 3000]
[manager application] <-------- response ---(2)---- [Vanguard 3000]
Set the state of an output line
(1) manager requests operation (NMEA msg: ACK)
(2) Vanguard 3000 acknowledges that the command has been executed by returning the updated output line state
(NMEA msg: XDR)
[manager application] ---(1)--- request ----------> [Vanguard 3000]
[manager application] <-------- ack --------(2)---- [Vanguard 3000]
Receive and acknowledge an alarm sent by the Vanguard 3000
(1) Vanguard 3000 sends alarm (NMEA msg: ALR)
(2) manager acknowledges alarm (NMEA msg: ACK)
[manager application] <-------- alarm ------(1)---- [Vanguard 3000]
[manager application] ---(2)--- ack --------------> [Vanguard 3000]