DIP Switch Address Calculator
Find which DIP switches to turn on for any address, or read the address a bank of switches is set to. Works for DMX512 lighting, Modbus devices, I²C chips and any binary switch bank, with a patch sheet for rows of DMX fixtures.
How to Use
- Pick the system: DMX512, Modbus, I²C or Generic. The presets set up common banks.
- Type the address you want. The drawing shows which switches go ON, or click the switches to see what address a bank is set to.
- Match the bank to your device: the number of switches, whether switch 1 is worth 1 (most gear) or the highest value, whether ON means 1, and the address with every switch off.
- For DMX, add the channels per fixture and how many fixtures to get start addresses and switch settings for the whole row.
- Check the warnings: DMX stops at 512, Modbus at 247, and I²C reserves 0x00–0x07 and 0x78–0x7F.
Worked Example
A DMX fixture at address 37. The switches are worth 1, 2, 4, 8, 16, 32, 64, 128 and 256. Take the largest that fits: 37 − 32 = 5, then 5 − 4 = 1, then 1 − 1 = 0. So 37 = 32 + 4 + 1, and switches 6, 3 and 1 go ON. In binary that is 0000100101, read from switch 10 down to switch 1.
A row of four 8-channel pars. Each fixture takes 8 channels, so the starts are 1, 9, 17 and 25. Address 1 is switch 1; 9 = 8 + 1 is switches 1 and 4; 17 = 16 + 1 is switches 1 and 5; 25 = 16 + 8 + 1 is switches 1, 4 and 5. The last fixture uses channels 25 to 32. At 8 channels a universe holds 64 such fixtures, the last starting at 505.
The common mistake: an offset fixture. If a light set to 37 answers on channel 38, it counts all switches off as address 1. The switches must then hold 37 − 1 = 36 = 32 + 4: switches 3 and 6, without switch 1.
Show Work
Formulas
DIP Switches, DMX and Bus Addresses
A DIP switch is a row of tiny switches in a dual in-line package, the same two-rows-of-pins shape as the chips around it, so it drops into the same holes on a circuit board. Before configuration was done in software, that was how hardware learned its settings: PC expansion cards had their I/O address and interrupt set on DIP switches and jumpers, and garage door openers and alarm panels stored their codes on them. Each switch is one bit, so n switches give 2n settings.
Stage lighting still uses them. DMX512 was published by the United States Institute for Theatre Technology (USITT) in 1986 to let lighting desks from different makers control the same dimmers, and became the ANSI standard E1.11 in 2004. One cable carries a universe of 512 channels, and each fixture listens from its start address for as many channels as it needs. Nine switches reach 511, which is why so many fixtures have ten.
Industrial buses work the same way. Modbus, introduced by Modicon in 1979 for its programmable controllers, allows slave addresses 1 to 247 on a serial line, with 0 kept for broadcast. I²C, created by Philips in 1982 for chips on one board, uses 7-bit addresses, and many chips tie two or three address bits to pins so that several of the same part can share a bus: a PCF8574 I/O expander answers anywhere from 0x20 to 0x27 depending on its A0 to A2 pins.
About This Calculator
This calculator converts between an address and the positions of a bank of up to 16 DIP switches, in either direction: type an address and the drawing shows which switches go ON, or click the switches to read the address. It handles banks numbered from either end, inverted logic, and an offset for gear that counts all switches off as 1 or as a base address.
For DMX it checks the 512-channel limit and builds a patch sheet for a row of identical fixtures; for Modbus it flags broadcast and reserved addresses; for I²C it flags reserved addresses and gives the 8-bit write and read forms. Everything runs in your browser.
Related tools: Number Base Converter, Chip Select / Address Decoder and the RS-485 Bias & Termination Calculator.
Frequently Asked Questions
How do I set a DMX address with DIP switches?
Each switch is worth double the one before it: switch 1 = 1, switch 2 = 2, then 4, 8, 16, 32, 64, 128 and 256 for switch 9. Turn on the switches whose values add up to the address. Address 100 = 64 + 32 + 4, so switches 3, 6 and 7 go ON; address 37 = 32 + 4 + 1, switches 1, 3 and 6.
What is switch 10 for on a DMX fixture?
It depends on the fixture. Many use switches 1 to 9 for the address (up to 511) and switch 10 for a function such as sound-active, standalone or follow mode. Others use switch 10 as the 512 switch, needed only for address 512. Check the manual before relying on it.
Why is my fixture one channel off?
Some fixtures treat all switches off as address 1, not 0, so the switches hold the address minus one. On those, address 37 needs 36 = 32 + 4: switches 3 and 6. Set “All switches off” to 1 to calculate for them. If the light still answers on the wrong channels, check whether its switches are numbered from the other end.
Which Modbus addresses can I use?
Slave addresses 1 to 247. Address 0 is broadcast, which every device on the bus obeys without replying, and 248 to 255 are reserved. Eight switches cover 0 to 255, so a bank can be set to an address the protocol will not answer to; this calculator warns when it is.
What does ON = 0 (inverted) mean?
On some boards a switch that is ON connects the input to ground, so the chip reads it as 0, and the switches that are OFF carry the value. Address 5 on such a 4-switch bank needs 0101 in binary, so switches 2 and 4 are ON rather than 1 and 3. If the manual shows the opposite of what this calculator says, try the inverted setting.
How do I use the DIP Switch Address Calculator?
Just type your numbers. The answer shows up right away — there is no button to press. Change anything and it updates by itself.
Is it free? Does it work without internet?
Yes to both. It is free with no sign-up, and once the page has loaded it keeps working even with no internet.
Where does my data go?
Nowhere — every calculation runs on your own device. Nothing you enter is uploaded, logged, or stored.
Common Use Cases
Stage and DJ lighting
Address a row of 8-channel par cans at 1, 9, 17 and 25 and get each fixture’s switches in one table.
Modbus RS-485 devices
Set a meter, drive or sensor to slave 12 with switches 3 and 4, and avoid 0 and 248 and above.
I²C address pins
A PCF8574 with A0 and A2 high sits at 0x25: 8-bit write 0x4A, read 0x4B.
Reading an unknown bank
Click the switches to match a board you have in hand and read the address it is set to.
Old PC cards and controllers
ISA cards, alarm panels and remote-control receivers set I/O addresses and codes with the same binary banks.
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