AW Gear Meters FEM-03 - Manual (Page 37)

FEM-03 Flow Monitor
Operation and Programming Manual
36
Serial Error Codes
If a read or write operation is not successful, the Fem-03 returns one of the following error messages:

NO1cr – Undefined command (something other than K/J)

NO2cr – allowable read range exceeded (addresses 0 to 500 [000H to 01F4H] allowed)

NO3cr – read error (read request exceeded 12 characters)

NO4cr – FEM detected a checksum error in the lower byte

NO5cr – FEM detected a checksum error in the higher byte
Checksum Calculation
The checksum calculation for the string variables in the Rate A PL read command would be as follows:
>01K000004XXcr
^^^^^^^^^^.......these characters are used in the calculation.
Add the values for the ASCII Decimal variables.
HEX 0 + 1 + K + 0 + 0 + 0 + 0 + 0 + 4
ASCII 48 + 49 + 75 + 48 + 48 + 48 + 48 + 48 + 52 = 464
To calculate the final checksum, convert the decimal number 464 into HEX (464=1D0 hex) and take the
last two characters (D0). The final string would look like this:
>01K000004D0cr
ASCII characters needed for checksum calculations are:
ASCII Decimal ASCII Decimal
0 48 A 65
1 49 B 66
2 50 C 67
3 51 D 68
4 52 E 69
5 53 F 70
6 54
7 55
8 56 J 74
9 57 K 75
Warning!