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RTD Function

Excel 2007+

Summary

The Excel RTD function enables real-time data retrieval from COM automation add-ins, providing dynamic updates from external data sources like stock quotes, market feeds, or custom applications without manual recalculation.

Syntax

RTD(progID, server, topic1, [topic2], ...)

Parameters

Parameter	Type	Required	Description
progID	`Text`	Yes	Name of the registered COM add-in ProgID in quotation marks
server	`Text`	Yes	Server name (" " for local) - use "" in VBA even locally
topic1	`Any`	Yes	Required first topic parameter for data identification
topic2	`Any`	No	Optional topics (up to 252 more for unique data combination

Using the RTD Function

RTD connects Excel to external real-time data sources through COM automation servers. Perfect for live financial data, sensor readings, or any application exposing data via COM interface. Unlike standard formulas, RTD updates continuously when the source changes.

Common RTD Examples

Basic RTD Server Connection

=RTD("mycomaddin.progid", "", "AAPL", "Price")

Retrieves live Apple stock price from local COM add-in (returns #N/A without server)

Remote Server Data Feed

=RTD("marketdata.server1", "datafeed.contoso.com", "EURUSD", "Bid")

Gets EUR/USD bid price from remote market data server

Multi-Topic Instrument Data

=RTD("trading.platform", "", "MSFT", "Quote", "Volume")

Fetches Microsoft stock quote and volume using multiple topic parameters

Frequently Asked Questions

#N/A appears when no COM automation add-in with the specified ProgID is registered locally. You must install and register a real-time data server first.

Yes, use "" (empty quotes) for local servers. In VBA, always use "" even for local execution.

Topic1 is required, with up to 252 optional topics (253 total parameters max).

Common Errors and Solutions

#N/A!

Cause: No registered COM add-in with specified ProgID

Solution: Install and register a compatible RTD server/add-in

#VALUE!

Cause: Invalid ProgID format or unregistered server

Solution: Verify ProgID spelling and COM registration

Server connection timeout

Cause: Network issues or server offline

Solution: Check server availability and network connectivity

Notes

Requires Windows COM automation add-in (cannot run on Mac Excel)
RTD formulas update automatically unlike other functions
Server must push updates via COM interface
Maximum 253 total parameters (progID + server + 251 topics)
Ideal for professional trading platforms and live dashboards

Compatibility

Available in: Excel 2007, Excel 2010, Excel 2013, Excel 2016, Excel 2019, Excel 2021, Microsoft 365

Not available in: Excel 2003 and earlier, Excel for Mac (no COM support)

Content last reviewed: December 9, 2025
Update frequency: As needed
Excel versions tested: Excel 2007+