PM864AK02控制處理器
時間同步
時間同步消息是高優(yōu)先級廣播類型的消息。NIS模塊立即為該消息類型提供服務(wù)。時間同步提供了一個通用的系統(tǒng)時基，用于排序異常報告、訪問趨勢數(shù)據(jù)和在系統(tǒng)控制臺上顯示。多播包含多個目的地數(shù)據(jù)的消息是多播消息。此郵件可以有一個到64個目的地。NIS POLL NIS輪詢消息是單個目標消息。NIS模塊使用此消息類型輪詢另一個節(jié)點的操作狀態(tài)。消息格式消息作為信息幀存在。每個幀由信息字段后面的消息控制字段組成。信息字段包含消息數(shù)據(jù)。它可以由多條消息組成，大小不一，最大可達1500字節(jié)。控制字段包含發(fā)起時間、序列、源、大小、循環(huán)計數(shù)、消息類型、目的地和校驗和值。NIS模塊遞增所有傳入消息的循環(huán)計數(shù)字段。當(dāng)消息計數(shù)字段達到256時，將丟棄下一條消息。這有助于將重試和虛假消息流量降至最低。NIS模塊使用消息類型確定如何處理消息。校驗和和循環(huán)冗余校驗碼字段驗證數(shù)據(jù)完整性。
信息傳輸
任何NIS模塊都可以在任何時候傳輸消息，而不考慮系統(tǒng)上任何其他NIS模塊的活動。每個NIS模塊可以同時發(fā)送和接收消息。NIS模塊的啟動或關(guān)閉是本地的，不需要與INFI-NET循環(huán)上的其他NIS模塊進行交互。每個NIS模塊接收所有傳入消息，并以存儲轉(zhuǎn)發(fā)方式將新的消息流傳輸?shù)较乱粋€節(jié)點。當(dāng)NIS模塊沒有要發(fā)送的消息時，NIS模塊將發(fā)送標志字符（空包）作為循環(huán)同步條件，以保持接收器處于鎖定狀態(tài)。NIS數(shù)據(jù)完整性NIS模塊使用三種方法確保數(shù)據(jù)完整性。它們是重試邏輯、節(jié)點狀態(tài)表和輪詢。重試邏輯如果在第一次消息傳輸時，NIS模塊沒有從目標節(jié)點接收到肯定或否定的確認，則它會重新發(fā)送十一次消息。如果在這一系列重試之后仍然沒有響應(yīng)，則目標節(jié)點被標記為脫機，并且NIS模塊將否定確認通知其他通信模塊。節(jié)點狀態(tài)表NIS模塊維護一個系統(tǒng)范圍內(nèi)狀態(tài)的內(nèi)部表，例如脫機和忙碌節(jié)點。NIS模塊將節(jié)點狀態(tài)更改中繼到其他通信模塊。當(dāng)NIS模塊定期輪詢節(jié)點時，它會相應(yīng)地更新此表
TIME SYNCHRONIZATION
The time synchronization message is a high priority broadcast type of message. The NIS module services this message type immediately. Time synchronization provides a common system time base to be used for sequencing exception reports, accessing trend data, and display on a system console. MULTICAST A message that contains data for multiple destinations is a multicast message. This message can have from one to 64 destinations. NIS POLL The NIS poll message is a single destination message. The NIS module uses this message type to poll the operational status of another node. MESSAGE FORMAT Messages exist as frames of information. Each frame consists of a message control field that follows an information field. The information field contains the message data. It can consist of multiple messages and vary in size to a maximum of 1,500 bytes. The control field contains time of origination, sequence, source, size, circulation count, message type, destinations, and checksum value. The NIS module increments the circulation count field of all incoming messages. When a message count field reaches 256, the next message is discarded. This is useful in keeping retry and spurious message traffic to a minimum. The NIS module uses the message type to determine how to process the message. The checksum and cyclic redundancy check code fields verify data integrity.
MESSAGE TRANSMISSION
Any NIS module can transmit a message at any time without regard to the activities of any other NIS module on the system. Each NIS module can transmit and receive messages simultaneously. NIS module start-up or shutdown is local and requires no interaction with other NIS modules on the INFI-NET loop. Each NIS module receives all incoming messages and transmits a new stream of messages in a store and forward fashion to the next node. When there are no messages for the NIS module to transmit, the NIS module transmits flag characters (null packets) as the loop synchronizing condition to keep the receivers in lock. NIS Data Integrity There are three methods the NIS module uses to insure data integrity. They are retry logic, node status table, and polling. RETRY LOGIC If on the first message transmission the NIS module does not receive a positive or negative acknowledgment from the destination node, it retransmits the message eleven times. If after this series of retries there is still no response, the destination node is marked off-line and the NIS module informs other communication modules of the negative acknowledgment. NODE STATUS TABLE The NIS module maintains an internal table of system wide status's such as off-line and busy nodes. The NIS module relays node status changes to other communication modules. When the NIS module periodically polls nodes, it updates this table accordingly
產(chǎn)品優(yōu)勢
1：國外專業(yè)的供貨渠道，具有價格優(yōu)勢
2：產(chǎn)品質(zhì)量保證，讓您售后無憂
3：全國快遞包郵
4：一對一服務(wù)
公司主營范圍簡介
PLC可編程控制器模塊，DCS卡件，ESD系統(tǒng)卡件，振動監(jiān)測系統(tǒng)卡件，汽輪機控制系統(tǒng)模塊，燃氣發(fā)電機備件等，優(yōu)勢品牌：Allen Bradley、BentlyNevada、ABB、Emerson Ovation、Honeywell DCS、Rockwell ICS Triplex、FOXBORO、Schneider PLC、GE Fanuc、Motorola、HIMA、TRICONEX、Prosoft等各種進口工業(yè)零部件、歐美進口模塊。
產(chǎn)品廣泛應(yīng)用于冶金、石油天然氣、玻璃制造業(yè)、鋁業(yè)、石油化工、煤礦、造紙印刷、紡織印染、機械、電子制造、汽車制造、塑膠機械、電力、水利、水處理/環(huán)保、鍋爐供暖、能源、輸配電等等
