I have a YN600EX RT II flash and a Yongnuo RF603II wireless transmitter, and I'm using a Canon 700D. If I am right from the research I have done, I don't have to use both transmitters to make my flash work as a radio slave; I just have to put one on my camera and it should trigger the flash's built-in radio system. But, I really can't get this thing to work and am out of ideas of what I've messed up.

For an example: I switch all 4 pins up in the trigger, and turn it to transmit only. In the flash, I find ETTL radio slave mode, choose channel one (for example), and in the flash ID I select all four digits to one each. It does nothing at all.

I have a feeling I haven't set the flash's ID the correct way, but I am out of ideas, and absolutely find no clue of how to synchronize these two together. If I put one receiver under the slave's hot shoe, then it works, but I want to operate it without it. What am I missing?

  • 1
    \$\begingroup\$ Putting all the dip switches in the "up" position on the RF-603 II, set it to Channel 16, not Channel 1. As a geek, though, I can't help thinking of it as Channel 15 where the channels are numbered 0-15 in binary. :) This, btw, is not your problem. \$\endgroup\$
    – inkista
    Aug 15, 2018 at 19:07

1 Answer 1


What you're missing is that Yongnuo has three different flash triggering systems:

  1. YN-560-TX and RF-60x manual-only triggering system.
  2. The YN-622/YN-622-TX TTL/HSS triggering system.
  3. The Yongnuo clones of the Canon "RT" triggering system.

All three groups use different radio signalling communication protocols. Your flash and its built-in trigger is from Group 3; your transmitter is from Group 1. These two groups are completely incompatible which is why your flash won't fire unless you put another RF-603 II to act as a receiver on its foot. Flashes that are in Group 2 with built-in triggers (e.g., the YN-685) can be used with Group 1 triggers, if put into 603 mode, but they can then no longer be used as TTL/HSS slaves. You can also trigger a Group 2 622-TX transmitter from a 560-TX transmitter, but again, no TTL/HSS.

Group 1 triggers, like the RF-603 II, are "manual only". The only things they can tell the remote flash are to fire and (if you shoot Canon or Nikon) to wakeup. A YN-560-TX transmitter can also control the power and zoom by group on the flashes with a built-in radio trigger (YN-560III, YN-560IV, YN-660, YN-720), but not on a flash on an RF-60x acting as a receiver unit. So, you won't have TTL, HSS, remote power control, or access to other flash settings (like ID codes). An RF-605 can add group on/off capability, but that's it.

Your best bet is probably to get a YN-E3-RT transmitter, which does speak "RT" and can do TTL, HSS, groups, ID codes, etc. with an RT flash. Or, to give up on Yongnuo and get Godox gear, where they only use one triggering system for everything. So if you just want to add a $65 manual-only speedlight to your fancy TTL/HSS one, you can. With Yongnuo, not so much.

If your flash/trigger are in the same group, then the basic troubleshooting routine to look at would be:

  1. Are all the batteries good/fully charged in everything?
  2. Are all contacts/hotshoes clear and clean of obstructions?
  3. Is everything set to the same channel?
  4. Is the transmitter fully seated forward in the camera hotshoe?
  5. If using an add-on trigger, is the flash fully seated forward onto the hotshoe of the trigger?
  6. If using a built-in trigger, is the flash in radio slave mode vs. an optical slave mode or on-camera mode?

See also:


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