EZT-550 Controller Manual
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Data Format in the Reply Message (Read Data Command)
When reading data from the EZT-550, the values must be deciphered from the ASCII codes in order to get
standard decimal values. In the following example, the read data from an operand in the EZT-50 is (30h 32h 43h
34h) which converted from ASCII codes to hexadecimal is 02C4.
Bit 15 Bit 0
The hexadecimal value of 02C4 must then be converted to decimal in order to get the actual value of 708.
9.2.3 BCC Block Check Calculation
For both the write and read commands, the BCC must be calculated and inserted into the command. The BCC
is used by the EZT-550 to make sure that the command sent was the command received. It does this by
calculating the BCC of the received command and comparing it to the BCC sent in the command to verify that
the received data is correct and has not been corrupted due to external noises or other causes. This calculation
must also be done by the computer in order to verify that the reply message is accurate.
The following example shows how to calculate the BCC by XOR summation of each byte in the message.
