MVME55006E-0163模块接口卡,MVME55006E-0163使用参数
在COMMREQ的FT输出上编程设备，例如设置线圈可选择的如果需要，此输出可以保持打开状态。在执行之前，有必要初始化命令块中的数据COMMREQ指令。由于正常的PLC扫描顺序是从上到下，在比包含的梯级更早的梯级中初始化命令块COMMREQ将满足此要求。如果使用移动指令将值加载到命令块寄存器中，请使用单词类型MOVE可加载十六进制数，整数类型MOVE可加载十六进制数十进制数。
MVME55006E-0163模块接口卡错误检测和处理如“COMMREQ状态字”所示，如果出现以下情况，则状态字返回值1：通信正常进行，但如果检测到任何错误情况，则该值大于返回大于1。如果需要在梯形图程序中检测错误，可以使用大于（GT）比较指令，以确定状态字中的值是否为负（小于零）。如果发生错误，GT指令的输出（Q）将变高。A.由输出驱动的线圈可用于启用故障处理或错误报告逻辑。COMMREQ的FT输出（如第4-6页所述）在某些故障和也可用于故障检测。此外，可以监视第一个状态字通过错误消息逻辑在操作员界面设备上显示，在这种情况下，状态文字代码将对应于屏幕上显示的相应错误消息操作员屏幕。要动态检查状态字，请写入一个非有效正数（0或99通常使用）输入到状态字中执行。如果指令执行成功，CPU将在那里写入数字1。此方法让您知道，如果数字1存在，则最后一个COMMREQ肯定存在已成功执行，并且1不仅仅是上次执行时留下的。当使用多个COMMREQ时，建议对每个COMMREQ进行验证在启用下一个之前成功通信。监视状态字是一个实现这一点的方法。
Programming a device, such as a Set Coil, on the FT output of the COMMREQ is
optional; this output may be left open if desired.
It is necessary to initialize the data in the Command Block before executing the
COMMREQ instruction. Since the normal PLC sweep order is from top to bottom,
initializing the Command Block in an earlier rung (or rungs) than the rung that contains
the COMMREQ will satisfy this requirement.
If you use MOVE instructions to load values into Command Block registers, use a
Word-type MOVE to load a hexadecimal number, and an Integer-type MOVE to load a
decimal number.
Error Detection and Handling
As shown in “COMMREQ Status Word”, a value of 1 is returned to the Status Word if
communications proceed normally, but if any error condition is detected, a value greater
than 1 is returned. If you require error detection in your ladder program, you can use a
Greater Than (GT) compare instruction to determine if the value in the Status Word is
negative (less than zero). If an error occurs, the GT instruction’s output (Q) will go high. A
coil driven by the output can be used to enable fault handling or error reporting logic.
The FT output of the COMMREQ, described on page 4-6, goes high for certain faults and
can be used for fault detection also. Additionally, the first Status Word can be monitored
by error message logic for display on an Operator Interface device, in which case, Status
Word codes would correspond to appropriate error messages that would display on the
operator screen.
To dynamically check the Status Word, write a non-significant positive number (0 or 99
are typically used) into the Status Word each time before its associated COMMREQ is
executed. If the instruction executes successfully, the CPU will write the number 1 there.
This method lets you know that if the number 1 is present, the last COMMREQ definitely
executed successfully, and that the 1 was not just left over from a previous execution.
When multiple COMMREQs are used, it is recommended that each be verified for
successful communications before the next is enabled. Monitoring the Status Word is one
way to accomplish this.
