HIEE320693R0001處理器卡件,HIEE320693R0001使用過(guò)程
用于90-30系列可編程邏輯的4通道模擬電壓輸入模塊控制器提供四個(gè)輸入通道，每個(gè)通道能夠?qū)⒛M輸入信號(hào)轉(zhuǎn)換為根據(jù)應(yīng)用要求使用的數(shù)字信號(hào)。模擬電壓輸入模塊為能夠轉(zhuǎn)換-10至+10伏范圍內(nèi)的輸入。每個(gè)四個(gè)通道是一毫秒。這為任何頻道轉(zhuǎn)換信號(hào)的分辨率為12位二進(jìn)制（4096中的1部分）。%AI寄存器中的用戶(hù)數(shù)據(jù)是16位2的補(bǔ)碼格式。
HIEE320693R0001處理器卡件12的位置%AI數(shù)據(jù)字中來(lái)自A/D轉(zhuǎn)換器的位如下所示。之間的關(guān)系A(chǔ)/D轉(zhuǎn)換器的電壓輸入和數(shù)據(jù)如圖3-10所示。模塊中還提供了有限電流輸入模式。在用戶(hù)身上提供跳線每個(gè)通道的端子連接器，可用于連接內(nèi)部250歐姆分流器電阻進(jìn)入電路。分流電阻器有效地提供–40至+40 mA的電流輸入范圍然而，輸入電流通常不應(yīng)超過(guò)±20 mA，以避免自熱和相應(yīng)的精度損失。4至20 mA輸入對(duì)應(yīng)于電壓輸入模塊的1至5伏輸入；因此，4到20 mA輸入的分辨率信號(hào)約為10位二進(jìn)制（1024中的1部分）。分辨率可以提高到使用精度為250歐姆的電阻器代替跳躍者電阻器使電壓輸入模塊將4至20 mA輸入視為2至10伏。
The 4-Channel Analog Voltage Input module for the Series 90-30 Programmable Logic
Controller provides four input channels, each capable of converting an analog input signal to a
digital signal for use as required by your application. The Analog Voltage Input module is
capable of converting inputs in the range of –10 to +10 volts. Conversion speed for each of the
four channels is one millisecond. This provides an update rate of four milliseconds for any
channel. Resolution of the converted signal is 12 bits binary (1 part in 4096).
User data in the %AI registers is in 16-bit 2’s complement format. The placement of the 12
bits from the A/D converter in the %AI data word is shown below. The relationship between
the voltage input and the data from the A/D converter is shown in Figure 3-10.A limited current input mode is also provided in the module. A jumper is provided on the user
terminal connector for each channel, which may be used to connect the internal 250 ohm shunt
resistor into the circuit. The shunt resistor effectively provides a –40 to +40 mA current input
range. However, the input current should generally not exceed ±20 mA, to avoid self-heating
of the input resistor and a corresponding loss of accuracy. A 4 to 20 mA input corresponds to a
1 to 5 volt input to the voltage input module; therefore, the resolution of the 4 to 20 mA input
signal is approximately 10 bits binary (1 part in 1024). The resolution can be increased to
approximately 11 bits (1 part in 2048) by using a precision 250 ohm resistor in place of the
jumper. The resistor causes the voltage input module to see a 4 to 20 mA input as 2 to 10 volts.
