HESG324442R13工控模块卡件
（字2）WAIT/NOWAIT标志：对于TCP/IP以太网通信，必须设置为零。COMMREQ状态字：以太网接口更新COMMREQ的状态字，以显示命令的成功或失败。命令字3和4指定COMMREQ状态字的PLC存储器位置。有关更多信息，请参阅本节中的COMMREQ状态字内存类型。（字3）COMMREQ状态字内存类型：此字指定COMMREQ状况字的内存类型。（字4）COMMREQ状态字地址偏移：此字包含所选内存类型内的偏移。状态字地址偏移量是一个从零开始的数字。例如，如果您希望%R1作为COMMREQ状态字的位置，则必须为偏移量指定零。%R100的偏移量为99位小数。然而，请注意，这将为每个COMMREQ使用唯一的COMMREQ状态（CRS）内存位置。▪ 在向给定信道发起信道命令COMMREQ之前，始终将COMMREQ状态字初始化为零。等待COMMREQ状态可通过监测通道错误和数据传输位确定未决传输何时完成。对于设置为发出多次读取的通道命令，只有在挂起的读取传输完成后才会发出下一次读取传输。PAC系统™ RX3i和RSTi EP TCP/IP以太网通信用户手册第8节GFK-2224Y 2019年8月编程SRTP信道命令150 8.3.2建立读取信道（2003）建立读取信道命令请求将信道与远程PLC关联，并将远程PLC的数据（定期）传输到本地PLC。命令块指定周期、从远程PLC执行的读取次数以及等待每次传输完成所允许的超时。无论指定的时间段如何，第一次读取都会立即执行。8.3.2.1示例命令块在IP地址10.0.0.1处建立到远程PLC的通道（通道5）。将COMMREQ状态字返回%R10。将远程PLC寄存器%R50–%R57读取到本地PLC寄存器%R100–%R107。重复用于读取的读取。该值必须介于1–32之间。如果信道号超出范围，则COMMREQ状态字中将出现命令错误指示。如果频道号与已使用的频道相同，则频道将重新分配任务以执行此新命令。（单词9）读取重复次数：单词9指定在自动完成通信请求并关闭频道之前要执行的读取次数。如果此值设置为1，则只发出一次读取。如果该值设置为0，将在请求的时间段内连续发出读取，直到通道中止。（单词10）读取周期的时间单位：单词10–11共同定义读取的频率（读取周期）。字10指定读取周期的时间单位，例如秒或分钟。单词11指定了这些单位的数量。时间单位的选择如下所示。对于读取周期：字11指定读取周期的时间单位数。即使通道命令设置为发出一次读取，读取周期也有效。读取周期计算示例：如果单词10包含指定秒为时间单位的值3，单词11包含值20，则读取周期为20秒。A通道命令集
(Word 2) WAIT/NOWAIT Flag: Must be set to zero for TCP/IP Ethernet Communications. COMMREQ Status Word: The Ethernet interface updates the COMMREQ status word to show success or failure of the command. Command words 3 and 4 specify the PLC memory location of the COMMREQ status word. For more information, refer to COMMREQ Status Word Memory Type in this section. (Word 3) COMMREQ Status Word Memory Type: This word specifies the memory type for the COMMREQ status word. (Word 4) COMMREQ Status Word Address Offset: This word contains the offset within the memory type selected. The status word address offset is a zero-based number. For example, if you want %R1 as the location of the COMMREQ status word, you must specify a zero for the offset. The offset for %R100 would be 99 decimal. Note, however, that this to use unique COMMREQ Status (CRS) memory locations for each COMMREQ. ▪ Always initialize the COMMREQ Status Word to zero before initiating a Channel command COMMREQ to a given channel. Wait for the COMMREQ Status can determine when the pending transfer completes by monitoring the Channel Error and Data Transfer bits. For Channel commands set up to issue multiple reads, the next read transfer will be issued only after the pending read transfer completes. PACSystems™ RX3i and RSTi-EP TCP/IP Ethernet Communications User Manual Section 8 GFK-2224Y August 2019 Programming SRTP Channel Commands 150 8.3.2 Establish Read Channel (2003) The Establish Read Channel command requests that a channel be associated with a remote PLC and that data from the remote PLC be transferred (periodically) to the local PLC. The Command Block specifies the period, the number of reads from the remote PLC to perform, and the timeout allowed in waiting for each transfer to complete. The first read is performed immediately, regardless of the period specified. 8.3.2.1 Example Command Block Establish a channel (Channel 5) to a remote PLC at IP address 10.0.0.1. Return the COMMREQ Status word to %R10. Read remote PLC registers %R50–%R57 to local PLC registers %R100–%R107. Repeat the read to be used for the read. This value must be in the range of 1–32. If the channel number is out of range, a command error indication will be placed in the COMMREQ Status word. If the channel number is the same as a channel already in use, the channel will be re-tasked to perform this new command. (Word 9) Number of Read Repetitions: Word 9 specifies the number of reads to be performed before automatically completing the communications request and closing the channel. If this value is set to 1, only a single read will be issued. If this value is set to 0, reads will be issued continuously on the requested period until the channel is aborted. (Word 10) Time Unit for Read Period: Words 10–11 together define how often the read is to be performed (read period). Word 10 specifies the time unit such as seconds or minutes for the read period. Word 11 specifies the number of those units. The choices for the time units are shown below. for Read Period: Word 11 specifies the number of time units for the read period. The read period is in effect even when the Channel command is setup to issue a single read. Example Read Period Calculation: If Word 10 contains a value of 3 specifying seconds as the time unit and Word 11 contains a value of 20, then the read period is 20 seconds. A Channel command set
