I suppose with enough thought, you _might_ be able to simulate the same bit patterns necessary to drive very specific LED strip sequences, but not every possibility.  That's because the RS485 output is expecting to send out at very discrete baud rate values, and will want to include things like intercharacter spacing, and various control bits to help the receiver properly interpret the validity and value of the transmitted characters (not signals) across the RS485 "network".

If all you want is DMX on/off control and can capture that in a way that can be replicated by a standard RS485 data transmission, then maybe you can perform rudimentary tasks, and slowly build up your library of available actions and allowable DMX addressing for the PLC to accurately and repeatedly produce on demand.

AutoGen_1822419

Dear Community,

We would like to control an LED strip with our S7-1214 DC/DC/DC PLC. This PLC is currently at the heart of our already existing control system, and the LED strip would be an add-on.

Most of the controllable LED strips use a protocol that is not compatible with the PLC. I was wondering if it is possible to communicate with an LED controller using the DMX protocol with the CB 1241 RS485 card, since the physical layer of DMX is the same as the physical layer of RS485.

I hope someone in the community can respond to this,

Thanks in advance,

Kind Regards,

Niels

 Nice project. Blinking lights are always nice projects. :-)

Swarley92

Hi!

I think the closest is with the CM PTP module. Take a look at this link.

There is not much documentation on CB1241 being used with this protocol.

The document you link to (thanks) has value but does not contain all the information. The document is about using a communication card that is part of the ET200 range.

The most important missing part is how the hardware configuration looks like. I was not able to duplicate what is written as there is no mention in the hardware configuration of the DMX protocol. It is not apparent to me how to configure to handle the inter framing "mark after break" signal.

The start frame (DMX_Data[0]) is not mentioned in great detail and should be included irrespective of how many other frames are used.

But now for the most important part:
The communication speed needs to be 250kbps which the S7-1200's communication boards/modules cannot handle. The fastest those can handle is 115.2kbps.

The S7-1200 cannot be used for the DMX512 protocol.

The topic starter can use the "Support Request" link if he feels that he needs an official answer from Siemens.

If you want to control addressable devices and LEDs using DMX, you will need to upgrade to the ET200 family (or higher if the budget allows).

The referenced link has documentation (pdf) showing a sample application of DMX and an S7 PLC.

109778975_ET200SP_CM_PtP_DMX512_DOC_V1_0_en.pdf (siemens.com)

AutoGen_1822419

Dear Community,

We would like to control an LED strip with our S7-1214 DC/DC/DC PLC. This PLC is currently at the heart of our already existing control system, and the LED strip would be an add-on.

Most of the controllable LED strips use a protocol that is not compatible with the PLC. I was wondering if it is possible to communicate with an LED controller using the DMX protocol with the CB 1241 RS485 card, since the physical layer of DMX is the same as the physical layer of RS485.

I hope someone in the community can respond to this,

Thanks in advance,

Kind Regards,

Niels

0_Einstein

If you want to control addressable devices and LEDs using DMX, you will need to upgrade to the ET200 family (or higher if the budget allows).

The referenced link has documentation (pdf) showing a sample application of DMX and an S7 PLC.

109778975_ET200SP_CM_PtP_DMX512_DOC_V1_0_en.pdf (siemens.com)

@0_Einstein: Do you notice what other people post? @Swarley92 already linked to the FAQ where the document is published which you mention now. 

@Niels: Consider using the comment section of the FAQ that @Swarley92 linked to communicate with Siemens about your query.

Hello,

if some one other want still use DMX and can't pay so much money for some Gateway or find some other LED strips with different protocol,  then it is also possible with cheap Wago 750 IO System and RS232/485 652 module where speed selectiuon can be done (better say DMX packets can be send/recv with some firmware version of module in case). Only sugestion that many possibilities are available to S7-1200 system Be careful again, any S7 controller with PN or PB capable interface and Master system can do this without problems, also with my mentioned Gateways. Your choice...