This function is called from YOUR application code to read coils from a Modbus slave.
Prototype
CPU_INT16U MBM_FC01_CoilRd (MODBUS_CH *pch,
CPU_INT08U slave_addr,
CPU_INT16U start_addr,
CPU_INT08U *p_coil_tbl,
CPU_INT16U nbr_coils);Arguments
pch
is a pointer to the channel (returned by MB_CfgCh()). This pointer specifies onto which channel the Modbus master will be communicating on. Of course, ‘pch’ must have been configured as a Master when you configured the channel.
...
is a pointer to an array of 8 bit values that will receive the value of all the coils you are reading. The size of the array needs to be at least (nbr_coils - 1) / 8 + 1. The format of the table is as follows:
MSB LSB B7 B6 B5 B4 B3 B2 B1 B0 ------------------------------------- p_coil_tbl[0] #8 #7 #1 p_coil_tbl[1] #16 #15 #9 : :
nbr_coils
specifies the number of coils you want to read from the slave.
Returned Value
MODBUS_ERR_NONE
if the call was successful.
...
If the expected number of bytes to receive doesn't correspond to the number of bytes received.
Notes / Warnings
None
Called By
Your Modbus master application.