MVME55006E-0163模塊接口卡,MVME55006E-0163使用參數(shù)
在COMMREQ的FT輸出上編程設備，例如設置線圈可選擇的如果需要，此輸出可以保持打開狀態(tài)。在執(zhí)行之前，有必要初始化命令塊中的數(shù)據(jù)COMMREQ指令。由于正常的PLC掃描順序是從上到下，在比包含的梯級更早的梯級中初始化命令塊COMMREQ將滿足此要求。如果使用移動指令將值加載到命令塊寄存器中，請使用單詞類型MOVE可加載十六進制數(shù)，整數(shù)類型MOVE可加載十六進制數(shù)十進制數(shù)。
MVME55006E-0163模塊接口卡錯誤檢測和處理如“COMMREQ狀態(tài)字”所示，如果出現(xiàn)以下情況，則狀態(tài)字返回值1：通信正常進行，但如果檢測到任何錯誤情況，則該值大于返回大于1。如果需要在梯形圖程序中檢測錯誤，可以使用大于（GT）比較指令，以確定狀態(tài)字中的值是否為負（小于零）。如果發(fā)生錯誤，GT指令的輸出（Q）將變高。A.由輸出驅(qū)動的線圈可用于啟用故障處理或錯誤報告邏輯。COMMREQ的FT輸出（如第4-6頁所述）在某些故障和也可用于故障檢測。此外，可以監(jiān)視第一個狀態(tài)字通過錯誤消息邏輯在操作員界面設備上顯示，在這種情況下，狀態(tài)文字代碼將對應于屏幕上顯示的相應錯誤消息操作員屏幕。要動態(tài)檢查狀態(tài)字，請寫入一個非有效正數(shù)（0或99通常使用）輸入到狀態(tài)字中執(zhí)行。如果指令執(zhí)行成功，CPU將在那里寫入數(shù)字1。此方法讓您知道，如果數(shù)字1存在，則最后一個COMMREQ肯定存在已成功執(zhí)行，并且1不僅僅是上次執(zhí)行時留下的。當使用多個COMMREQ時，建議對每個COMMREQ進行驗證在啟用下一個之前成功通信。監(jiān)視狀態(tài)字是一個實現(xiàn)這一點的方法。
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.
