I'm currently working at a customer site to develop an interactive form with a barcode on it. I have certain preferences I need to keep in mind when developing: The barcode should not be larger than 5.868cm(width)x2,665cm(height) (thats 2inx0.74in), the data should be in a semicolon-separated string and contains about 1500 - 1800 characters. After various tests and what I have read in these forums (Barcoded Forms and Designer 7) I'm not quite sure I can size the barcode with these preferences.
In one of the postings here I found a calculation on how to determine the width and height of a barcode based on rows and columns:
width = num columns * 17 * module-length
height = num rows * Y/Y ratio * module-length
Am I right that the multiplication of columns and rows give me the maximum amount of data I can put into the barcode? But what indicates this number then, ASCII-characters or bytes?
Has anyone had any experience with these calculations? Can I rely on these?
Also, I did some test in Designer: I put in a paper form barcode object and a simple textfield. I resized the barcode to match my requirements, and set the max textfield length to 255. And received a red circle at design time indicating that the barcode is too small or the amount of data too large! When I set the length to 97 the red circle disappeared!
From above calculations I got a number of 10 columns and 39 rows, but you can't tell me that this means just 97 ASCII-characters!!!
I'm really very, very confused. Any help in sizing the barcode is greatly appreciated and urgently needed!
If I was to generate random strings containing characters from a list of upper case characters " ABC DEF GHI JKL MNO PQR STU VWX YZ;" then you could probably get 40 characters into the barcode of that size succesfully. Again, all upper case, and using a semi-colon as a seperator.
The data you are looking to encode you would have to use a very large PDF417 Barcode (maximum size of 928 codewords) and then you also have to think about the data content. If you are using upper and lower case or special characters you cut your data capacity almost in half. The other factor is the error correction level. If you are going to be faxing the document the ECC has to be higher which means the data capacity will be even lower.
The specifications of PDF417 are a little more complex that just the rows times the height.
Send me an email directly (firstname.lastname@example.org) and I will send you a sample form that I use that randomly generates data based on a string you select, and then lets you size barcodes on the form with different ECC levels to give you a good idea of the capacity of each of them.