HESG324428 DCS模块卡件
内存组C（字节模式）离散系统内存组C。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154 8.3.3建立写入信道（2004）建立写入信道命令请求将信道连接到远程PLC，并将本地PLC的数据（定期）传输到远程PLC。命令块指定要执行的周期、对服务器（远程PLC）的写入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，都会立即执行第一次写入。8.3.3.1示例命令块在IP地址处建立远程PLC的写入通道（通道6），从客户端到服务器的传输次数为指定数量。（字8）通道编号：字8指定用于写入的通道。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。（字9）写入重复次数：字9指定在自动完成通信请求并关闭通道之前要执行的写入次数。如果此值设置为1，则只发出一次写入。如果此值设置为0，将在请求的时间段内发出写入，直到通道中止。（单词10）写入周期的时间单位：单词10–11共同定义写入的频率（写入周期）。字10指定写入周期的时间单位，例如秒或分钟。单词11指定了这些单位的数量。时间单位的选择有：值表示百分之一秒（10ms）十分之二秒（100ms）3秒4分钟5小时PACSystems™ 写入周期的RX3i时间单位。即使通道命令设置为发出一次写入，写入周期也有效。写入周期计算示例：如果单词10包含指定秒为时间单位的值3，而单词11包含值20，则写入周期为20秒。设置为发出单个写入的通道命令只能有一个挂起的写入传输。通常在每个写入周期开始时发出写入。如果在写入期间未完成挂起的写入传输，则通道错误位和详细通道状态字将被设置为指示非致命周期错误。如果周期错误发生在第一次传输时，COMMREQ状态也将指示非致命周期错误。如果时间单位数为零，则上一次传输完成后，将立即发出后续传输。在这种情况下，信道错误位不报告周期错误。（字12）每次写入超时：字12指定以太网接口在设置通道错误位和详细通道状态位以指示非致命超时错误之前等待写入传输完成的时间（以百分之一秒为单位）。如果第一次传输时发生超时错误，COMMREQ状态（也将指示非致命超时错误。对于大多数应用程序，不需要超时，因为写入周期充当超时。（如果没有超时，字12应为零。）但是，有两种特殊情况建议指定超时：▪ 当时间单位数（字11）为零时，以便在上一次传输完成后立即发出后续传输，并且不会报告周期错误。在这种情况下，可以指定超时值，以便通道错误位报告超时错误。▪ 写入周期非常长（分钟或小时）时。在这种情况下，可以指定一个较短的超时值，这样应用程序就不必等到写入周期到期后再采取操作。（字13）本地PLC-存储器类型：字13–14指定本地PLC中以太网接口将获取要写入远程PLC的数据的位置。单词13的有效值在“建立读取通道”的描述中列出。要传输的数据量由写入远程PLC（字17）的数据的存储单元数指定。（字14）本地PLC-内存启动
memory group C (byte mode) Discrete system memory group C (bit mode) %S 19 30 84 Discrete system memory (byte mode) Discrete system memory (bit mode) %G 56 86 Discrete global data table (byte mode) Discrete global data table (bit mode) Note: The Program Name and servers only. PACSystems™ RX3i and RSTi-EP TCP/IP Ethernet Communications User Manual Section 8 GFK-2224Y August 2019 Programming SRTP Channel Commands 154 8.3.3 Establish Write Channel (2004) The Establish Write Channel command requests that a channel be connected to a remote PLC and that data from the local PLC be transferred (periodically) to the remote PLC. The Command Block specifies the period, the number of writes to the server (remote PLC) to perform, and the timeout allowed in waiting for each transfer to complete. The first write is performed immediately, regardless of the period specified. 8.3.3.1 Example Command Block Establish a write channel (Channel 6) to a remote PLC at IP address the specified number of transfers from the client to the server. (Word 8) Channel Number: Word 8 specifies the channel to be used for the write. 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 Write Repetitions: Word 9 specifies the number of writes to be performed before automatically completing the communications request and closing the channel. If this value is set to 1, only a single write will be issued. If this value is set to 0, writes will be issued on the requested period until the channel is aborted. (Word 10) Time Units for Write Period: Words 10–11 together define how often the write is to be performed (write period). Word 10 specifies the time unit such as seconds or minutes for the write period. Word 11 specifies the number of those units. The choices for the time units are: Value Meaning 1 hundredths of seconds (10ms) 2 tenths of seconds (100ms) 3 Seconds 4 minutes 5 hours PACSystems™ RX3i time units for the write period. The write period is in effect even when the Channel command is setup to issue a single write. Example Write 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 write period is 20 seconds. A Channel command set up to issue a single write can have only one pending write transfer. A write will normally be issued at the start of each write period. If the pending write transfer has not completed during the write period, the Channel Error bit and Detailed Channel Status words will be set to indicate a non-fatal period error. If the period error occurs on the first transfer, the COMMREQ Status will also indicate a non-fatal period error. If the Number of Time Units is zero, a subsequent transfer will be issued as soon as the previous transfer completes. In this case, no period errors are reported by the Channel Error bit. (Word 12) Timeout for Each Write: Word 12 specifies the time (in hundredths of a second) the Ethernet interface will wait for a write transfer to complete before setting the Channel Error bit and Detailed Channel Status bits to indicate a non-fatal timeout error. If the timeout error occurs on the first transfer, the COMMREQ Status (will also indicate a non-fatal timeout error. For most applications, a timeout is not needed because the write period acts as a timeout. (Word 12 should be zero for no timeout.) However, there are two special circumstances in which specifying a timeout is recommended: ▪ When the number of time units (Word 11) is zero, so that a subsequent transfer will be issued as soon as the previous transfer completes and no period errors are reported. In this case, a timeout value can be specified so that the Channel Error bit will report timeout errors. ▪ When the write period is very long (minutes or hours). In this case, a shorter timeout value can be specified so the application doesn’t have to wait for the write period to expire before taking action. (Word 13) Local PLC - Memory Type: Words 13–14 specify the location in the local PLC where the Ethernet interface will get the data to be written to the remote PLC. Valid values for Word 13 are listed in the description of Establish Read Channel. The amount of data to be transferred is specified by the number of memory units of the data written to the remote PLC (Word 17). (Word 14) Local PLC - Memory Starting
