3BHE020357P201產(chǎn)品外觀，ABB輸入卡件
登記結(jié)果位置必須包含用戶編程的四個字節(jié)數(shù)據(jù)這四個字節(jié)的數(shù)據(jù)駐留在異常向量表中，并指向中斷服務(wù)例程的位置。中斷服務(wù)例程讀取數(shù)據(jù)來自雙端口寄存器，然后返回主程序。
4.4.10外部觸發(fā)操作電路板可以響應外部TTL脈沖（激活需要低或“零”脈沖）單個a/D轉(zhuǎn)換或a/D轉(zhuǎn)換掃描將啟動。首先，用戶通過向CSR和選擇隨機模式或掃描模式，但不設(shè)置EN啟動CSR中的轉(zhuǎn)換H位（D13）。
3BHE020357P201產(chǎn)品外觀控制位ENA EXT STRT H（D11）必須改為設(shè)置為“一”。這將在P2外產(chǎn)生TTL高電平（邏輯“1”）連接器引腳A31，用于向外部設(shè)備發(fā)送信號，表明電路板已準備好接收外部觸發(fā)器。至少100納秒的外部邏輯電平（“零”）觸發(fā)脈沖然后可以通過P2連接器引腳A27輸入到電路板。這將啟動A/D轉(zhuǎn)換取決于先前選擇的A/D模式。除了啟用外部觸發(fā)器操作外，還有一些必須安裝跳線，以將P2連接器引腳電氣連接到外部觸發(fā)電路。關(guān)于選擇這些跳線，請參閱第5.4.4節(jié)。是請注意，其他板有時會使用P2輸入/輸出引腳來執(zhí)行不同的操作輸入/輸出功能。這需要從系統(tǒng)角度進行檢查，以驗證是否存在沒有多個驅(qū)動器/接收器使用這些P2輸入/輸出線：P2-A31、A32、A27和A28。4.5更改A/D操作模式電路板在自動掃描模式下通電。切換進入任何其他A/D操作模式時，必須執(zhí)行軟件重置順序在重新編程新的A/D操作模式之前執(zhí)行。此序列包括：（1）寫入控制字，設(shè)置軟件復位H（D9）位和新的A/D模式（D8到D6），（2）寫入控制字以清除軟件重置H（D9）位，包括新的A/D模式（D8到D6），（3） 接下來重寫A/D模式，并在控件中設(shè)置EN START CONV H（D13）word啟動A/D轉(zhuǎn)換序列。
只有在切換到操作模式時，才需要上述順序自動掃描模式以外的模式。任何其他模式開關(guān)都可以通過改變控制中的模式位（D8到D6）直接編程登記表4.5-1顯示了要切換到的正確順序和控制字其他四種A/D操作模式。
Register. The resulting location must contain a user-programmed four bytes of
data. These four bytes of data reside in the exception vector table and point to the
location of the Interrupt Service routine. The Interrupt Service routine reads in the
data from the dual port registers and then returns to the main program.
4.4.10 External Trigger Operation
The board may be enabled to respond to an external TTL pulse (active
low or "zero" pulse required) a single A/D conversion or a scan of A/D conversions
will be initiated. First, the user selects the A/D mode to be used by writing to the
CSR and selecting a RANDOM MODE or SCANNING MODE, but do not set the EN
START CONV H bit (D13) in the CSR. The control bit ENA EXT STRT H (D11)
must be set to a "one" instead. This will generate a TTL high (logic "one") out the P2
connector pin A31 to signal the external equipment that the board is ready to receive
an External Trigger. An external logic level ("zero") trigger pulse of at least 100 ns
may then be input to the board via the P2 connector pin A27. This will start the A/D
conversion(s) depending on the A/D Mode which was previously selected.
In addition to enabling the External Trigger operation there are some
jumpers which must be installed to electrically connect the P2 connector pins to the
External Trigger circuitry. Refer to Section 5.4.4 on selecting these jumpers. Be
aware that the P2 I/O pins are sometimes used by other boards to perform different
I/O functions. This needs to be checked from a system viewpoint to verify there are
not multiple drivers/receivers using these P2 I/O lines: P2-A31, A32, A27, and A28.
4.5 CHANGING A/D OPERATING MODES
The board powers up in the AUTO SCANNING MODE. To switch the
board into any of the other A/D operating modes, a software reset sequence must be
performed before reprogramming the new A/D operating mode. This sequence
includes: (1) writing a control word setting the SOFTWARE RESET H (D9) bit and
the new A/D Mode (D8 through D6), (2) writing a control word clearing the
SOFTWARE RESET H (D9) bit and including the new A/D mode (D8 through D6),
(3) next rewrite the A/D mode and set the EN START CONV H (D13) in the control
word to start the A/D conversion sequence.
The above sequence is only necessary when switching to an operating
mode other than the AUTO SCANNING MODE. Any other mode switch can be
directly programmed by changing the mode bits (D8 through D6) in the Control
Register.
Table 4.5-1 shows the proper sequence and control words to switch to
the four other A/D operating modes.
