Mitsubishi MELSEC Address Converter
MELSEC device numbers with the right radix — octal X/Y on FX5, hex on iQ-R.
X / Y are octal on this series
Careful — “X20” is also valid on MELSEC iQ-R, but there it means point 32, not 16.
X20 · X21 · X22 · X23 · X24 · X25 · X26 · X27
This tool reads a MELSEC device address with the radix its CPU series actually uses. Pick iQ-R or iQ-F/FX5, enter something like X20, D100 or W1F, and it returns the device number as a plain integer, the radix it was written in, and the same physical point written for the other series. Reference: X20 is point 16 on FX5 (octal) but point 32 on iQ-R (hexadecimal).
How it works
A MELSEC address is a device symbol followed by a device number, and the number is not always decimal. Mitsubishi's device list gives a notation per device: inputs and outputs are octal on the iQ-F / FX5 family and hexadecimal on iQ-R, while the internal relay M and the data register D are decimal on both. That is why FX inputs jump from X7 straight to X10, and why an iQ-R happily accepts XF. The tool applies the table for the series you select and refuses digits that radix cannot contain, so a typo like X8 on an FX is reported instead of silently becoming something else.
The conversion matters most when a program moves between families. Because the two series write the same point differently, copying an I/O list across without re-basing the numbers shifts every address — and it shifts them by an amount that grows as the numbers do, so a quick check of the first few points looks fine. Converting through the underlying point index, as this tool does, keeps the physical terminal the same.
Worked example
iQ-R · X20 → hexadecimal → point 32
the FX5 point 16 written for iQ-R → X10
FX5 · X8 → rejected — octal has no digit 8
D100 → decimal on both series → point 100
Device notation
| Parameter | Value | Notes |
|---|---|---|
| X, Y — iQ-F / FX5 | Octal | digits 0-7 |
| X, Y — iQ-R | Hexadecimal | digits 0-9 A-F |
| M, L, F, S | Decimal | both series |
| D, R | Decimal | both series |
| T, ST, C, LC | Decimal | both series |
| B, SB | Hexadecimal | both series |
| W, SW | Hexadecimal | both series |
| SM, SD | Decimal | both series |
Source: MELSEC iQ-R CPU Module User's Manual (Application), SH-081264ENG §22.1 Device List; MELSEC iQ-F FX5 User's Manual (Application), JY997D55401AD §4.1 List of Devices.
FAQ
▸Why is there no X8 or X9 on an FX controller?
Because X and Y device numbers on the MELSEC iQ-F / FX5 series are written in octal, and octal has no digits 8 or 9. The inputs run X0 to X7 and then continue at X10 — which is the eighth input, not the tenth. The device list in the FX5 User's Manual (Application) states the notation for every device.
▸Does X20 mean the same thing on iQ-R and FX5?
No, and this is the trap when porting a program. On FX5 the X devices are octal, so X20 is point 16. On MELSEC iQ-R they are hexadecimal, so the same text X20 is point 32. The physical point that FX5 calls X20 is written X10 on an iQ-R.
▸Which devices are not affected by the series?
The decimal ones. M (internal relay), D (data register), L, F, T, ST, C, LC, SM and SD are decimal on both series, so D100 is device 100 either way. The link devices B, SB, W and SW are hexadecimal on both. It is specifically X and Y whose radix differs.
▸Where do these radices come from?
From the device list tables in Mitsubishi's own manuals: the MELSEC iQ-R CPU Module User's Manual (Application), document SH-081264ENG, section 22.1; and the MELSEC iQ-F FX5 User's Manual (Application), document JY997D55401AD, section 4.1. Each table has a Notation column giving the radix per device. Series whose manuals have not been checked are deliberately not offered here rather than assumed to match.
▸Does it cover Q and L series?
Not yet. Only the two series above have been verified against their manuals. Rather than assume the Q and L series behave like iQ-R, they are left out until their device lists are confirmed — a wrong radix silently addresses the wrong point.
▸Is anything uploaded?
No. Every address is parsed locally in your browser.