Modulation Frequency issue - Description

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Thierry D
Posts: 7
Joined: Fri Nov 20, 2020 11:21 pm

Modulation Frequency issue - Description

Post by Thierry D »


Again this PID works with a lot of other equipments we had to adapt in case as they have a bug.
Madrix has some difficulties to show the 3x type of Modulation available.

Get seems not working as it ishould be .

Data Description:
Modulation Setting Requested: It is working fine

This field is a 32-bit unsigned integer representation of the frequency in Hz for the requested setting for machine readable applications.
It looks like that you are not dealing with Frequency at all which is incorrect towards the standard

Text Description: has an issue
The ASCII text field contains up to 32 characters of description information for the modulation setting.
In the description we added (xxxhz) for tools/controllers not dealing with frequency.

Sully Expected Madrix
Modulation Frequency Description Frequency Description
1 0 Without PWM (0Hz) none Without PWM (0Hz)
2 3200 PWM (3K2Hz) (3200Hz) none PWM (3K2Hz) (3200hz)
3 17000 PWM (17Khz) (17000Hz) none (0Hz)

For modulation 3 the description (OHz) is not correct.
It looks like Madrix does not like starting with the same Text (we had a similar issue with a known console and we had to adapt but the final result in other tools is not as neat).

Posts: 5
Joined: Fri Feb 16, 2018 12:02 pm

Re: Modulation Frequency issue - Description

Post by FishAI »

Hi Thierry,

similar to your post regarding the curves issue we are not talking about the specific get command for MODULATION_FREQUENCY but the command MODULATION_FREQUENCY_DESCRIPTION. MODULATION_FREQUENCY does not provide any information you have mentioned in your report.

You quoted E1.37-1 correct, it says the frequency field uses a 32-bit unsigned integer representation for machine readable applications. This describes the data field provided in this command. It is not said that any RDM Controller must use this value at all.
Therefore we would not disrespecting the RDM standard even if MADRIX RADAR ignores this value.
Could you please further elaborate how MADRIX RADAR should use this information?

MADRIX RADAR reads the frequency information from the MODULATION_FREQUENCY_DESCRIPTION command and appends it in brackets to the reported text description, just as you do. This gives you the doubled values in the text field "3200 PWM (3K2Hz) (3200Hz)", where "3200 PWM (3K2Hz)" is the text description the fixture supplied and " (3200Hz)" is the text MADRIX RADAR generates from the frequency information supplied in the frequency field. Both values are read from the MODULATION_FREQUENCY_DESCRIPTION command.

This is also the case with the third modulation setting, where "17000 PWM (17Khz) (17000Hz) none" is the 32 characters string the fixture reported and " (0Hz)" is the supplied frequency from the frequency field of MODULATION_FREQUENCY_DESCRIPTION appended to the text description by MADRIX RADAR.
Note that this string can be longer than 32 characters, as RDM only defines the limitations of 32 character during the transmission of the data via DMX512, not for display purposes.

As the 0Hz for the third setting seems to be incorrect, please make sure you are setting the frequency field of this modulation setting to 0x4268 (17000) and not 0x0000 by accident.

It would be great if you share a Wireshark record containing the communication with the fixture. Please attach it to your forum post for public viewing or send it to
This is generally a good idea for discussing any protocol related problems.

Best regards
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