# How Do I Transmit the Code 39 Check Digit?

Article ID: 34049753

### Issue / Question

How do I make the scanner transmit the Code 39 check digit?

### Applicable To

Barcode scanners

To enable the transmission of the Code 39 Check Digit, the Enable Code 39 Check Digit programming bar code must be scanned followed by the Transmit Code 39 Check Digit.  The code with check digit is referred to as Code 39 mod 43. To compute this, each character is assigned a value. The assignments are listed in the table above, and almost, but not quite, systematic.

Here is how to do the checksum calculation:

1. Take the value (0 through 42) of each character in the barcode excluding start and stop codes.
2. Sum the values.
3. Divide the result by 43.
4. The remainder is the value of the checksum character to be appended.

Example 1:
The
check digit of Code 39 string data converts the numbers from Code 39’s character values table.

• C = 12
• O = 24
• D = 13
• E = 14
• 3 = 3
• 9 = 9

12(C) + 24(O) + 13(D) + 14(E) + 3 + 9 = 75 - 43 = 32

Results: 32
= W based on the character values table. The check digit for Code 39's data is W.

Example 2:
In case of scan data 04465AZ120:

0 + 4 + 4 + 6 + 5 + 10(A) + 35(Z) + 1 + 2 + 0 + 38(space) + 38(space) = 143 - 43 = 100 - 43 = 57 - 43 = 14

Results: 14 = E based on the character values table. The check digit of the above data is E.

Test Scenario 1:

1. Scan the Factory default barcode 2. Connect to Host PC with HID mode > Scan CODE39W barcode > Check the output data from the Notepad app.  3. If you want to ignore the check digit value, enable the Code 39 Check digit verification and disable the Transmit Code 39 Check Digit.

Test Scenario 2:
1. Scan the Code 39 Check Digit Verification barcode. 2. Scan the Do Not Transmit Code 39 Check Digit barcode.  NOTE Code 39 Check Digit Verification must be enabled for this parameter to function.

Then scan test with CODE39W, the result’s CODE39 without W.
1. If you want to have the Check digit(W) again, scan the barcode below. Then scan test with CODE39W, the result’s CODE39W. This same setting can be configured via 123Scan. 