I never tried using RS-232 control until a couple of days ago when I started experimenting via my MX-1200 and MSC-400. I could use a bit of help.

I have three components capable of RS-232 control-an LG TV, a Yamaha AV receiver and an Oppo UHD blu-ray player. I started by trying to get the power on and power off codes to work for each component. I had very little trouble getting them to work for the receiver and the blu-ray player however, the TV has stumped me, so far.

The TV (LG OLED65E6P) is different from the other two components in that it doesn't have a nine pin connector but instead has a 3.5mm input jack for RS-232 control. I'm not completely clear as to which cable to use. My initial attempt utilized a 3.5mm to 3.5mm stereo cable, but after a few attempts, I couldn't get it to work. Other choices would seem to be 3.5mm to 3.5mm mono cable (seems unlikely) and, perhaps, two RS-232 cables (one male, one female) hooked together. I'd appreciate some input on which cable to use since nothing's going to work without getting this first step right.

If the cable was the only issue, I would just try all of the options, however, it's complicated because the OLED65E6P isn't in the URC database nor are any other LG OLED's, as far as I can see. Also, I'm not yet knowledgeable enough to manually input the codes (I have the LG external control deice setup document). The URC database has 45 possible serial codes for LG TV's so there are a lot to try.

While none of the codes (only three so far) I tried worked, something must have happened because after the tests, the TV would no longer respond to IR control, including the original remote. I had to unplug the TV to get it to respond again.

If anyone can shed some light on which cable to use and/or, which code to use from the database, it would be greatly appreciated.

Serial control basically comes down to three wires: Tx, or transmit; Rx, or receive; and ground. Stop thinking of the mini plugs as mono or stereo and think of them as different conductors.

The sleeve is the ground. With some devices, the tip is Tx and the ring is Rx; with some devices it's the reverse. This is the case with the old Pronto cables and URC cables, for instance.

Also, the Tx of one device connects to the Rx of the other device. You'll want to label sketches of how you're wiring things so you can keep things straight.

Ernie is correct.

You need to look in the MSC-400 manual. Ports 6-12 on an MSC-400 are multi-purpose and can be serial or IR. It uses a special tip-ring1-ring2-sleeve 3.5mm connector. You will need to get the correct pin out for the TXD, RXD and ground. A "stereo" 3.5mm cable will not work.

Looking in the LG external control device setup manual indicates the following:

Tip-receive (RXD)
Ring-transmit (TXD)
Sleeve-ground (GND)

Looking in the CCP MSC-400 programming manual indicates the following:
Tip-N/C
Ring 1-transmit (TX)
Ring 2-receive (RX)
Ring 3-ground (GND)

It sounds like I need to make a custom cable which connects the transmit of the TV to the receive of the MSC-400, connects the transmit of the MSC-400 to the receive of the TV and connects the two grounds. The question is how do I make this? Please correct me below if I err in the steps listed:

1. Make sure I have a connector with a tip and three rings for the MSC-400 and a connector with a tip and two rings, or as Ernie says, a tip, ring and sleeve, for the TV.
2. Wire the transmit of the MSC connector to the receive of the TV connector, the receive of the MSC connector to the transmit of the TV connector and wire the two grounds together.

I'm wondering if I really need to make a custom cable or if I can create one from two I already have. or can get? What about connecting the URC RS-232M cable to a computer cable with a female DB9 connector on one end and a two ring 3.5mm connector on the other end? This would only work if the pin assignments are correct. The TV's external control device setup manual indicates two possibilities using pins 2, 3 and 5 (2 and 3 either transmit and receive or receive and transmit). Do you think this would work or should I just cut off the nine pin connector from a URC RS-232 cable and wire it manually to the two ring 3.5mm connector? Any suggestions would be greatly appreciated.

It sounds like you're on the right track.

You can absolutely splice a tip, ring, sleeve connector to a tip, ring, ring, sleeve connector. Just use a multi-meter set to continuity to verify which color wire goes to which connector pin. I would doing this to verify communication and then you can always make a "pretty" cable for the finished product.

I would also suggest using a terminal program on your computer to verify all your serial commands are functional before programming the control system. Connect straight to the TV from your computer and test. Obviously, you would need a different cable.

Before making a custom cable to enable use of the TV's 3.5mm jack, I realized the TV also has multiple USB in ports and I have a USB to serial converter. I connected the converter to the URC RS232F cable on port 7. Anything I should know about doing this rather than utilizing the 3.5mm input? I've not yet gotten it to work but I've only barely started testing.

Don't. You'd need the TV to have & support a driver for whatever model of USB-RS-232, and also to NOT power down the USB ports when the TV is shut off.

+1

You're adding a humongous layer of complication to this. You may never get it working like that. The key is to verify your commands work and then to be able to get reliable control from your system.

My recommendation...

1) Verify serial commands are correct and working. Use a terminal program on your computer and test codes directly from computer to TV.

2) Make a cable for testing. It can be spliced and ugly. We just want to make sure it works.

3) Add serial commands to your control system and test directly from the MSC-400.

4) Add serial commands to macros and/or buttons on remote.

5) Make a pretty cable, if you desire.

Just did an LG with an MC3 used a crossover DB9 without issue.

Great point about the TV powering down the USB ports when it's off. Mine does (light goes out on Keyspan device) so this would seem to rule out the USB approach.

Sounds like I should just cut the DB9 connector off of a URC RS232 cable and splice it together with a two ring 3.5mm plug. Will have to get another URC RS232 cable as the two I have are being used for my Oppo UHD Blu-ray player and Yamaha AV receiver.

I've never seen a three ring 3.5mm connector other than on the URC RS232 cables. Any chance I could find a connector like this or it easiest to just cut the end off a URC cable?

Just curious-what type of crossover DB9 cable? I see several types but don't know anything about these.

Cutting off a URC cable would probably be the easiest - maybe not the cheapest. I bought a pack of T,R,R,S connectors off eBay a while ago. You would have to solder your connections.

I don't remember what I searched for but they didn't cost much.

TRRS breakout

I never heard of TRRS before. Not knowing that term, all I've ever seen are two ring (mono) and three ring (stereo) cables and adapters. Will make the cable and see if I can get it to work. Thanks so much for all the help and the education!

I ended up using, for now, the two cables I described earlier-a URC RS232 cable and a standard computer cable with a DB9 connector on one end and a three conductor 3.5mm connector on the other end. Hooking these two together didn't work initially, however, as I learned from this thread, the receive and transmit wires must be cross connected. Once I got a DB9 null modem adapter, and put it between the other two cables, everything worked great. May make a "prettier", and shorter, cable later. Thanks again to everyone who helped with my education.

Still, I need to ask for a bit more assistance. I've got all the basic commands working from my MX-1200 with one critical exception-the home or "My Apps" command. Unfortunately, the URC serial database seems to be well out of date when it comes to LG TV's. It certainly doesn't reflect my OLED65E6P.

Searching the database yielded all the commands except the one so I turned to the LG external control device setup document. I don't fully understand what's in this document as it only seems to show RS232 information for commands not included on the remote control. For instance it reflects commands for "power on" and "power off" but not the "power" toggle command. It does have a table for the commands included on the remote control such as the needed "My Apps" command. I'm confused as to whether these commands can be sent via the serial connection, however, I would assume so, particularly since I found all of them but the one I still need in the URC serial database. The table lists the "My Apps" command as having a code (hexa) of 42. Is there some way to enter this code manually through CCP that I don't yet know? I know commands can be entered manually and I have seen how to modify URC serial database commands yet I'm not sure how to get this one command working. Seems like I still have a bit to learn. Any assistance would be greatly appreciated.