Decode and Calculate Bitmap field for ISO8583 transactions

Learn ISO8583 Bitmap by example

The easiest way to learn ISO8583 bitmaps is by example

Enable bitmap fields

Check the boxes on the left side and press Calculate Bitmap. The watch the bitmap change in the BINARY representation

If you do not select any check boxes, you will get a bitmap with only zeroes. This is not an invalid value, but means that NO fields are activated (present) in the ISO8583 message.

Bitmap = "map of bits"

The BINARY representation is the actual map of bits in binary. Each ISO8583 field is represented as a 0 or 1 in this string or array of bits. This is represented only for our understanding.

This binary representation is NOT a valid bitmap to send or receive because we need the value of the bytes.

Bitmap BINARY value

To obtain the bitmap binary value, we must group every 8 bits into a byte.

The binary form (the bytes) cannot be represented in ASCII, because they do not represent characters. So for us humans to read and write binary values, we must represent them in hexadecimal, on the left side

The Bitmap binary value cannot always be represented in ASCII. To see that, try to copy the HEX representation and paste it in the HEX to ASCII converter

ISO8583 bitmaps: BINARY or HEX

The bitmap is loaded in ISO8583 messages in BINARY or ASCII representation of HEX. Not ASCII representation of binary

Bitmap ASCII - the calculated bitmap HEX value on the left is exactly loaded in the message, as ASCII text

Bitmap BINARY - you will see this hex representation if you have a hex dump of the ISO8583 Message