The DIP switch is used to set the machine type (washer or dryer) and the number for the card reader. The DIP switch is located directly on the card reader circuit board:

Switch 1 sets the machine type (Down for Washer, Up for Dryer) and the other 7 switches set the machine number using a binary system, which is documented at the bottom of this page. You can number up to 127 washer readers and 127 dryer readers using the this DIP switch. This table shows the switch positions depending on the required machine/reader number.

For readers on equipment that are not laundry machines (e.g soap dispensers), the position of switch 1 does not matter.

Explanation of the math behind DIP switch
The right most switch (switch 8) is the least significant bit, with a value of 1 if it is in the upper position, and a value of 0 if in the lower position. The 7th switch from the right (switch 2) is the most significant bit, with a value of 64 (2 raised to the power of 6) if in the upper position, and a value of zero in the lower position.

The machine number is simply the sum of the values of switches in the upper position. So if the 1st and 2nd switches are in the upper position, the number is 1+2=3. If the 1st and 3rd switches are in upper position, the machine number is 1+4=5. If the 2nd and 4th switches are in the upper position, the machine number is 2+8=10.