# Mitsubishi TCP SLMP Writing Bad\_NotSupported

**URL:** <https://forum.inductiveautomation.com/t/mitsubishi-tcp-slmp-writing-bad-notsupported/102232>\
**Category:** Ignition\
**Tags:** ignition81, perspective\
**Created:** [February 12, 2025, 7:09am UTC](https://forum.inductiveautomation.com/t/mitsubishi-tcp-slmp-writing-bad-notsupported/102232 "2025-02-12T07:09:38Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![wilmerolsson](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/wilmerolsson/32/85888_2.png) [@wilmerolsson](https://forum.inductiveautomation.com/u/wilmerolsson)\
**Post date:** [February 12, 2025, 7:09am UTC](https://forum.inductiveautomation.com/t/mitsubishi-tcp-slmp-writing-bad-notsupported/102232/1 "2025-02-12T07:09:38Z")

</div>

Hi!

I've successfully connected to a Mitsubishi PLC (FX5U) with IQ-F in Ignition. I can read the tags but i can only seem to write to words. When i try to write to a bool/bit i get "Bad\_NotSupported: The requested operation is not supported."

Could i have missed something here?

 ![bild](https://us1.discourse-cdn.com/inductiveautomation/original/3X/6/8/684627594e737c5f15d6fe6994d1c87d762b1f56.png)  
 ![bild](https://us1.discourse-cdn.com/inductiveautomation/original/3X/f/f/ff8eaccf6dcb5f0cf65406ee927f5c6d433bd8aa.png)

---

<div class="post-metadata">

**Author:** ![wilmerolsson](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/wilmerolsson/32/85888_2.png) [@wilmerolsson](https://forum.inductiveautomation.com/u/wilmerolsson)\
**Post date:** [February 12, 2025, 7:23am UTC](https://forum.inductiveautomation.com/t/mitsubishi-tcp-slmp-writing-bad-notsupported/102232/2 "2025-02-12T07:23:59Z")

</div>

I found my own answer:

Optional Bit Index

Bit indexing can be specified on any integer data type to retrieve a boolean value at a bit position. Addresses with a bit index are read-only and any attempts to write to them will result in a Bad\_NotSupported error due to the MELSEC protocol.

A bit index cannot be specified for the following:

```
Non-integer data types (bool, float, double, and string)
Non-scalar addresses (arrays)

```

> **[Mitsubishi TCP Driver | Ignition User Manual](https://www.docs.inductiveautomation.com/docs/8.1/ignition-modules/opc-ua/opc-ua-drivers/mitsubishi-tcp-driver#addressing-in-the-designer)**
>
> The Mitsubishi TCP driver provides a user interface in the Gateway where you can create, import, or export addresses when connected to devices that support the MELSEC protocol. After setup, configured tags will be browsable in the OPC Browser of the...