HIEE305111R0001机械设备卡件
手册第12节GFK-2314T 2019年9月带HART通信的模拟模块571 11.8将HART数据转换为RX3i格式当仅使用HART传递COMMREQ（命令2）时，HART数据必须是字节封装的，并且是HART规范定义的大端格式。由于PACSystems CPU使用小端格式，浮点值和ASCII数据必须由程序逻辑重新格式化。注意，当使用COMMREQ 1或自动扫描的HART数据时，不需要此转换。Proficy Machine Edition 5.5版工具箱中的两个功能块可用于打包/解包HART ASCII数据：▪ ASCII_PACK在发送至HART模块之前准备ASCII数据。▪ ASCII_UNPACK可用于解包HART设备返回的ASCII字符。这些将在下一节中介绍。11.8.1转换浮点数据（Endian Flip）从传递请求的字17开始的浮点值必须转换为大端格式。从应答的第7个字开始的浮点值必须从大端格式转换。基本程序是通过SWAP_DWORD（大小=1）和SWAP_WORD（大小=2）函数传递任何HART浮点值，如下图所示。这将交换浮点DWORD中的字，并交换两个浮点字中的字节。在此示例中，显示了如何在发送HART命令34“写入阻尼值”之前格式化浮点数据。PACSystems*RX3i系统手册第12节GFK-2314T 2019年9月带HART通信的模拟模块572图327：使用交换DWord和交换字的梯形逻辑11.8.2 ASCII_PACK ASCII_PAACK在使用COMMREQ2（HART直通请求）将ASCII数据发送至HART模块之前准备ASCII数据。所有功能块参数均为Type=WORD、Pass By=Value或Type=WORD和Pass By=Reference的字数组。可以使用所有基于单词的参考记忆类型和符号。可以对数组数据使用不同类型的数据（例如，使用数据的字节数组作为ASCII_PACKED和ASCII_UNPACKED块的输入），尽管机器版在验证期间会发出警告。在上述示例中，输入字节数组的大小需要至少与功能块参数字数组的数据大小一样大。ASCII_UNPACK ASCII_UNPACK可用于解包HART设备在响应COMMREQ 2发送的直通应答数据中返回的ASCII字符。所有功能块参数均为Type=WORD、Pass By=Value或Type=WORD和Pass By=Reference的字数组。来自应用程序的所有斜坡模式开启命令。在渐变模式中，输出通道在一段时间内渐变到新值，而不是立即获取新值。可以为所有输入通道设置高报警限值和低报警限值，并且可以向CPU报告每个输出通道的开路故障（电流输出模式）。版本BA及更高版本支持插入和从通电的RX3i通用背板中取出。参见第2.6.4.1节热插拔。模块支持使用WinLoader软件实用程序（如果主机CPU具有串行端口）或使用基于Web的工具（如果主机没有串行端口）进行固件升级。固件升级套件中包含说明。23 12.1.2隔离+24V直流电源此模块必须从外部电源接收24Vdc电源。如果模块位于RX3i通用背板中，则可通过背板左侧的TB1连接器或直接在模块接线板上连接外部电源。如果模块位于扩展背板中，则外部电源必须连接到此模块的接线板。12.1.3 LED：ALG442 PACSystems*RX3i系统手册第13节GFK-2314T 9月。
Manual Section 12 GFK-2314T Sept. 2019 Analog Modules with HART Communications 571 11.8 Converting HART Data to / from RX3i Format When using HART Pass-Through COMMREQ (command 2) only, HART data must be both byte-packed and in big-endian format as defined by the HART Specification. Because PACSystems CPUs use little-endian format, floating-point values and ASCII data must be reformatted by the program logic. Note that this conversion is not required when using COMMREQ 1 or for HART data that is automatically scanned. Two function blocks in the Proficy Machine Edition release 5.5 toolchest can be used to pack/unpack HART ASCII data: ▪ ASCII_PACK prepares ASCII data before sending it to a HART module. ▪ ASCII_UNPACK can be used to unpack ASCII characters returned by a HART device. These are described in the next section. 11.8.1 Converting Floating-Point Data (Endian Flip) Floating-point values that begin at word 17 of a Pass-Through Request must be converted to big-endian format. Floating-point values that begin at word 7 of the reply must be converted from big-endian format. The basic procedure is to pass any HART float values through the SWAP_DWORD (size = 1) and SWAP_WORD (size = 2) functions, as displayed in the following figure. This swaps the words within the float DWord, and swaps the bytes within the two float words. In this example shows how to format floating-point data prior to sending HART command 34, Write Damping Value. PACSystems* RX3i System Manual Section 12 GFK-2314T Sept. 2019 Analog Modules with HART Communications 572 Figure 327: Ladder Logic Using Swap DWord & Swap Word 11.8.2 ASCII_PACK ASCII_PACK prepares ASCII data before sending it to a HART module using COMMREQ2 (HART Pass-Through Request). All of the function block parameters are either Type = WORD, Pass-By = Value or word arrays of Type = WORD and Pass-by = Reference. All word-based reference memory types and symbolics can be used. It is possible to use data of a different type for the array data (for example, using a byte array of data as input to the ASCII_PACKED and ASCII_UNPACKED blocks), although Machine Edition will issue a warning during verification. In the example mentioned, the size of the input byte array would need to be at least as large as the data size of the function block parameter word array. ASCII_UNPACK ASCII_UNPACK can be used to unpack ASCII characters returned by a HART device in Pass-Through Reply data send in response to COMMREQ 2. All of the function block parameters are either Type = WORD, Pass-By = Value or word arrays of Type = WORD and Pass-by = Reference. All ramp mode on command from the application program. In ramp mode, the output channel ramps to a new value over a period of time, rather than taking the new value immediately. High and low alarm limits can be set for all input channels and an open-wire fault (current output modes) can be reported to the CPU for each output channel. Revision BA & later supports insertion into and removal from an RX3i Universal Backplane which is under power. Refer to Hot Insertion and Removal, Section 2.6.4.1. Module supports firmware upgrades using the WinLoader software utility (if the host CPU has a serial port) or using a Web-based tool (if the host CPU has no serial port). Instructions are included with the firmware upgrade kit.23 12.1.2 Isolated +24Vdc Power This module must receive 24Vdc power from an external source. If the module is located in an RX3i Universal Backplane, the external source can be connected via the TB1 connector on the left side of the backplane or directly on the module terminal block. If the module is located in an Expansion Backplane, the external source must be connected to the terminal block of this module. 12.1.3 LEDs: ALG442 PACSystems* RX3i System Manual Section 13 GFK-2314T Sept.
