Master function

Write and read access to various slaves is possible using the F145 and F146 instructions. Individual access to each slave as well as global transmission is possible.

1.  (1) Master
2.  (2) Slave

Procedure for master communication

1. Set communication parameters

   Required settings: communication mode (MEWTOCOL-COM or Modbus RTU), station number, baud rate, communication format

2. Execute write or read instruction

   Use one of the following instructions:

   Instruction	Application	Restrictions
   F145_WRITE_DATA	Easy to use for communication with Panasonic devices supporting the MEWTOCOL-COM or Modbus RTU slave function	Devices must have matching address areas
   F146_READ_DATA
   F145_WRITE_DATA_TYPE_OFFS		–
   F146_READ_DATA_TYPE_OFFS
   F145F146_MODBUS_MASTER	For communication with any device supporting the Modbus RTU protocol	For station numbers 1–99 only, start register range of 0–32764 Start register range of 0–65535

3. Evaluate flags

   Use one of the following instructions:

   Method	Comment
   IsF145F146NotActive	Returns the value of the "F145/F146 not active" flag. It is TRUE if the execution of an F145 or F146 instruction is possible because neither instruction is active.
   sys_bIsComPort1F145F146NotActive sys_bIsComPort2F145F146NotActive	These system variables are TRUE if the execution of an F145 or F146 instruction is possible because neither instruction is active.
   IsF145F146Error	Returns the value of the "F145/F146 error" flag. It is TRUE if the execution of an F145 or F146 instruction has terminated with an error.
   sys_bIsComPort1F145F146Error sys_bIsComPort2F145F146Error	These system variables are TRUE if the execution of an F145 or F146 instruction has terminated with an error.
   sys_wComPort1F145F146ErrorCode sys_bIsComPort2F145F146ErrorCode	These system variables contain the error code if transmission has terminated with an error.