The checksum is a 2's complement, if you have a 2 bytes, you do: byte1 + byte2 = 0x..... The result is then inverted(if it is a 0,change it into a 1 or if it a 1,change it into 0) and add 1 to the inverted byte.
About the carriage return, we found that yesterday itself. Does your slave communicate with master using 9bit transmission or does your slave communicates with RS485 device with 9bit transmission?
Yes, the master communicates with the slave using 9bit tranmission, it has to be this way.
My slave must communicate with RS485 device with 9bit transmission as well
send data frame from your managers's software to master PIC. Write the received frame to eeprom in your PIC. Then disconnect your managers software because you have to use com port with reatterm. Now reset you PIC and you should read your eeprom contents and send it to uart and receive it in realterm . See what data comes.
if you write data (frame 5 bytes) to eeprom addresses like 0x00, 0x01, 0x02, 0x03, 0x04, then read those address and send the read data to realterm.