Something that may make PLM programming easier to approach. There will not be multiple commands stack up in the PLM or executed waiting for a response. Basically it is issue a command. get a response (which could be multiple messages in response), issue the next command, get the next response. Multiple Group commands cannot be initiated. Insteon will allow only one Group sequence to be active at a time. This is true even for device to device. If a paddle/button is pressed involving several responders and another paddle/button is pressed on another device which initiates another Group sequence, the current group sequence will be aborted in favor of the new one. Generally this has no visual effect since the initial Group Broadcast will cause all responders to react so the follow-up Group Cleanup messages that are cancelled would normally be redundant.