1756-IF8 是 ControlLogix 产品系列中的一款模拟量输入模块

1756-IF8 是 ControlLogix 产品系列中的一款模拟量输入模块

Allen-Bradley 1756-IF8 是 ControlLogix 可编程自动化控制器 （PAC） 系列的模拟输入模块。该模拟输入模块具有八 （8） 个输入通道，可配置为各种输入信号，例如 +/-10VDC、0-10VDC 和 0-5VDC 电压信号以及 0-20 mA 电流信号。该模块通常用于连接模拟信号生成仪器和设备，例如变送器、变送器、信号分配器、信号隔离器、面板仪表和其他具有类似功能的设备。

1756-IF8 是一款具有高分辨率转换的单插槽模块。它具有不同的分辨率，从 15 位到 16 位。特定模块分辨率为 ±10.25V：+/-320VDC 为 15 μV/count（10 位加符号双极性），160 μV/count（16 位）;对于 0-10VDC，80 μ/V 计数（16 位）;用于 0-5VDC 和 0...20.5mA：0-32 mA信号为16.0 μA/计数（20位）。

此模块的安装实例数量几乎没有限制。大多数 ControlLogix 控制器能够处理多达 4000 个模拟 I/O 信号。1756-IF8 可以安装在控制器沿线的本地机箱中，也可以安装在分布式 I/O 机架内。

1756-IF8 使用 Sigma-Delta 转换方法，将接收到的信号保存在整数模式（左对齐，2 秒补码）IEEE 32 位浮点寄存器中。它使用 1756-TBCH 和 1756-TBSH 可拆卸接线端子 （RTB），具有用户定义的机械键控。

模块扫描时间也因接线配置而异。对于单点差分接线，扫描时间为 16-488 ms，对于 4 点差分，扫描时间为 8-244 ms，而 5-122 ms 为 2 点差分输入。

1756-IF8 可以通过三种不同的方式接线：单端接线、差分接线和高速模式差分接线。在单端布线中，所有输入设备都连接到一个公共接地，并允许将信号输入的一侧与信号接地进行比较。然后，模块使用差值为控制器生成数字数据。使用单端接线方法可以最大限度地增加模块可用通道的数量。当您的应用可能具有单独的信号对或公共接地不可用时，以及当您需要提高环境中的抗噪能力时，应使用差分布线。这种接线方法中的通道彼此之间并不完全隔离。但是，当您需要尽可能快的数据更新时，您应该使用高速模式差分接线方法。请注意，此模式仅允许使用模块上每四个通道中的一个通道。1756-IF8 的具体功能包括模块滤波器、欠量程/超量程检测、过程报警、断线检测、多个输入范围、实时采样、数字滤波器和速率报警。其背板电压和电流额定值为 5.1 伏直流电，最大值为 150 毫安，直流电压为 24 伏，最大值为 40 毫安。它的输入电流范围为 4 至 20 毫安，输入电压范围为 -10 至 10 伏。功耗为 1.73 瓦，最大过压保护为 30 伏直流电（电压）和 8 伏直流电（电流）。

1756-IF8 是 ControlLogix 产品系列中的一款模拟量输入模块

Allen-Bradley 1756-IF8 is an analog input module for the ControlLogix Programmable Automation Controller (PAC) family. The analog input module has eight (8) input channels that can be configured for various input signals, such as +/-10VDC, 0-10VDC, and 0-5VDC voltage signals, and 0-20 mA current signals. The module is commonly used to connect analog signal generation instruments and devices, such as transmitters, transmitters, signal splitters, signal isolators, panel meters, and other devices with similar functions.

The 1756-IF8 is a single slot module with high resolution conversion. It has different resolutions, from 15 bits to 16 bits. The specific module resolution is ±10.25V: +/-320VDC is 15 μV/count (10-bit plus sign bipolar), 160 μV/count (16-bit); For 0-10VDC, 80 μ/V count (16 bits); For 0-5VDC and 0... 20.5mA: The 0-32 mA signal is 16.0 μA/ count (20 bits).

There is almost no limit to the number of installed instances of this module. Most ControlLogix controllers are capable of handling up to 4,000 analog I/O signals. The 1756-IF8 can be installed in a local chassis along the controller line or in a distributed I/O rack.

The 1756-IF8 uses the Sigma-Delta conversion method to store the received signal in an integer mode (left-justified, 2-second complement) IEEE 32-bit floating point register. It uses 1756-TBCH and 1756-TBSH detachable terminal blocks (RTB) with user-defined mechanical keying.

Module scan times also vary depending on the wiring configuration. The scan time is 16-488 ms for a single-point differential connection, 8-244 ms for a 4-point differential connection, and 5-122 ms for a 2-point differential input.

The 1756-IF8 can be wired in three different ways: single-ended, differential, and high-speed differential. In single-ended wiring, all input devices are connected to a common ground and allow the side of the signal input to be compared to the signal ground. The module then uses the difference to generate digital data for the controller. Using the single-ended wiring method maximizes the number of channels available to the module. Differential wiring should be used when your application may have a separate signal pair or when common ground is not available, and when you need to improve noise resistance in your environment. The channels in this wiring method are not completely isolated from each other. However, when you need data updates as fast as possible, you should use the high-speed mode differential wiring method. Note that only one of every four channels on the module is allowed in this mode. Specific features of the 1756-IF8 include modular filters, underrange/overrange detection, process alarm, line break detection, multiple input ranges, real-time sampling, digital filters, and rate alarms. Its backplane voltage and current ratings are 5.1 volts DC with a maximum of 150 mA and 24 volts DC with a maximum of 40 mA. It has an input current range of 4 to 20 mA and an input voltage range of -10 to 10 volts. The power consumption is 1.73 watts and the maximum overvoltage protection is 30 volts DC (voltage) and 8 volts DC (current).