IC687RCM711B使用過程,GE燃機(jī)卡
改進(jìn)的高頻抑制選項(xiàng)，則J2為已安裝，不應(yīng)移除。所有RFILT輸入SIP將被占用具有SIP標(biāo)頭。這些是0的SIP電阻器?. J1可能已安裝，但未安裝必需的這些SIP為輸入源提供VME接地參考。隔離輸入源（如3V/5V輸入模塊）需要這種配置防止高頻噪聲成為共模信號導(dǎo)致輸出數(shù)據(jù)波動。
5.4.3.2輸入電壓范圍輸入電壓范圍由跳線J4-1、2、3控制。最大滿負(fù)荷標(biāo)度范圍為20 V。要將滿標(biāo)度范圍修改為10 V，請配置跳線如表5.3-1所示。所有輸入電壓必須在VMEbus的12 V范圍內(nèi)線性操作的地面。對于“一”以外的增益，所有輸入電壓必須為VMEbus接地10 V以內(nèi)。對于單端操作，接地感應(yīng)計(jì)為輸入。
IC687RCM711B使用過程5.4.3.3雙極或單極操作模擬輸入的雙極或單極操作通過跳線J3-1、2、3如表5.3-1所示。5.4.4外部觸發(fā)跳線說明外部觸發(fā)電路允許用戶輸入TTL電平“零”至啟動A/D轉(zhuǎn)換或A/D轉(zhuǎn)換掃描序列。此輸入必須為通過安裝跳線J9和J10啟用PC連接器。J9允許接地參考連接。J10啟用觸發(fā)信號，并標(biāo)記為EXT STRT在示意圖上轉(zhuǎn)換L（SH6）。除了跳投，ENA EXT STRT必須在控制寄存器中設(shè)置H（D11）。該信號也被帶到用戶通過P2連接器。外部電路可以監(jiān)測該TTL信號，當(dāng)其高達(dá)邏輯“1”時(shí)，電路板已準(zhǔn)備好進(jìn)行下一個(gè)STRT轉(zhuǎn)換輸入以開始轉(zhuǎn)換。表5.4.4-1給出了外部觸發(fā)信號。內(nèi)部定時(shí)器-16、32或48位定時(shí)器選擇內(nèi)部定時(shí)器（8254）有三個(gè)16位計(jì)數(shù)器。這三個(gè)計(jì)時(shí)器可以通過跳線生成16、32或48的最大計(jì)數(shù)長度位（請參閱第4.4.6節(jié)以確定計(jì)數(shù)器分辨率和編程）。表5.4.5-1顯示了可能的跳線配置。A/D掃描序列長度跳線配置三種掃描模式（自動掃描模式、掃描輪詢模式、掃描中斷模式）使用J6處的跳線確定掃描多少通道。掃描始終從通道0開始，然后繼續(xù)使用下一個(gè)更高的通道，直到J6與通道總數(shù)匹配已掃描。例如，出廠設(shè)置通過以下方式執(zhí)行所有64個(gè)通道（0到63）在J6中編碼64。J6-1是最高有效位。J6-7是最低有效位。J6-1、J6-2、J6-3、J6-4、J6-5、J6-6、J6-7的權(quán)重為64、32、16、8、4、2和1通道。安裝的跳線表示“零”。表5.4.6-1給出了針對不同掃描長度安裝跳線的一些示例?？匆姷?.6.1節(jié)了解跳線設(shè)置的限制
Frequency Rejection option is ordered, J2 is
installed and should NOT be removed. All of the RFILT input SIPs will be occupied
with SIP headers. These are SIP resistors of 0 ?. J1 may be installed but it is not
necessary. These SIPs supply the input source with the VME ground reference.
Isolated input sources, such as the 3V/5V input modules, require this configuration
to prevent high frequency noise from becoming a common mode signal and
causing fluctuations in the output data.
5.4.3.2 Input Voltage Range
Input voltage range is controlled by jumpers J4-1, 2, 3. The maximum full
scale range is 20 V. To modify the full scale range to 10 V configure the jumpers
as indicated in Table 5.3-1. All input voltages must be within 12 V of VMEbus
ground for linear operation. For gains other than "one", all input voltages must be
within 10 V of VMEbus ground. For single-ended operation, the ground sense
counts as an input.
5.4.3.3 Bipolar or Unipolar Operation
Bipolar or unipolar operation of the analog inputs is selected with
jumpers J3-1, 2, 3 as indicated in Table 5.3-1.
5.4.4 External Trigger Jumper Description
The external trigger circuitry allows the user to input a TTL level "zero" to
start an A/D conversion or an A/D conversion scan sequence. This input must be
enabled to the PC connector by installing jumpers J9 and J10. J9 allows a ground
reference connection. J10 enables the trigger signal and is labeled EXT STRT
CONVERT L on the schematic (SH6). In addition to the jumper, the ENA EXT STRT
H (D11) must be set in the control register. This signal is also brought out to the
user via the P2 connector. External circuitry can monitor this TTL signal, and when it goes High to a logic "one" then the board is ready for the EXT STRT CONVERT L
input to begin a conversion(s). Table 5.4.4-1 gives the connector description for the
External Trigger signal.
Internal Timer - 16-, 32-, or 48-Bit Timer Selection
The internal timer (8254) has three 16-bit counters. These three timers
may be jumpered in a way to generate a maximum count length of 16, 32, or 48
bits (refer to Section 4.4.6 to determine counter resolution and programming).
Table 5.4.5-1 shows the possible jumper configurations. A/D Scan Sequence Length Jumper Configuration
The three scanning modes (AUTO SCANNING MODE, SCANNING
POLL MODE, SCANNING INTERRUPT MODE) use the jumpers at J6 to determine
how many channels to scan. Scans always begin with Channel 0 and continue
with the next higher channel until J6 matches the total number of channels
scanned. For example, the factory setting does all 64 channels (0 through 63) by
encoding 64 in J6. J6-1 is the most significant bit. J6-7 is the least significant bit.
J6-1, J6-2, J6-3, J6-4, J6-5, J6-6, J6-7 have weights of 64, 32, 16, 8, 4, 2, and 1
channels, respectively. An installed jumper signifies a "zero". Table 5.4.6-1 gives
some examples of the jumpers to be installed for different scan lengths. See
Section 3.6.1 for restrictions on jumper settings.
