Steve, Answers to your three questions: If I power on the Pi with the second RIM unplugged from USB, the unit boots up and the heart beat on the first RIM is normal. If I subsequently plug in the second RIM, its heartbeat flashes normally (after about 2 seconds) and the first RIM stays up, both heartbeats are flashing, not quite synchronously, but appear to wig-wag. Life is good. If I power up the node with both RIMs connected, the first RIM heartbeat comes on first, much slower than normal, and blinks irregularly for about 3-4 seconds. Then the second RIM heartbeat starts to flash normally, and the first RIM stops flashing with the heartbeat LED on steady. (this lsusb report is with both RIMs plugged in, and the Pi powered up – RIM #1 heartbeat on steady, RIM #2 heartbeat flashing normally) root@28336:~# lsusb Bus 001 Device 005: ID 0d8c:013a C-Media Electronics, Inc. Bus 001 Device 004: ID 0d8c:013a C-Media Electronics, Inc. Bus 001 Device 003: ID 0424:ec00 Standard Microsystems Corp. SMSC9512/9514 Fast Ethernet Adapter Bus 001 Device 002: ID 0424:9514 Standard Microsystems Corp. Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub root@28336:~# (this lsusb report is with the Pi booted with RIM #1 only, and the second RIM plugged in after boot. Both RIM heartbeats flashing normally) root@28336:~# lsusb Bus 001 Device 004: ID 0d8c:013a C-Media Electronics, Inc. Bus 001 Device 005: ID 0d8c:013a C-Media Electronics, Inc. Bus 001 Device 003: ID 0424:ec00 Standard Microsystems Corp. SMSC9512/9514 Fast Ethernet Adapter Bus 001 Device 002: ID 0424:9514 Standard Microsystems Corp. Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub root@28336:~# (this lsusb report is with the Pi booted with RIM #1 only, the second RIM was left unplugged) root@28336:~# lsusb Bus 001 Device 004: ID 0d8c:013a C-Media Electronics, Inc. Bus 001 Device 003: ID 0424:ec00 Standard Microsystems Corp. SMSC9512/9514 Fast Ethernet Adapter Bus 001 Device 002: ID 0424:9514 Standard Microsystems Corp. Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub root@28336:~# In all three cases, no other usb devices were connected. No keyboard, no mouse. The 3rd and 4th USB connectors are empty. channel driver is usbradio in rpt.conf, rxchannel = radio/usb for first node, and rxchannel = radio/usb2 for the second node. ** This does not match the instructions in the allstarlink.org “setting up a two node system” how-to page. ** In usbradio.conf (at the end of [usb] stanzas) I added these lines since I am using the RIM interface pins to control a set of 4 relays. Prior to adding these lines, USB communications would fail because output was not declared. The second RIM on node 2 has no relay board, so these lines are not present in the [usb2] section of usbradio.conf gpio5=out1 ; in, out0 or out1 gpio6=out1 ; in, out0 or out1 gpio7=out1 ; in, out0 or out1 gpio8=out1 ; in, out0 or out1 28336*CLI> core show version Asterisk 1521 built by root @ repeater on a armv7l running Linux on 2015-10-17 03:09:22 UTC 28336*CLI> Rpi2_dial.img was downloaded 11/26/2016 from allstarlink.org portal Thank you, Tom Cooney, Jr., W3SF tom@cooneyjr.com Home: (814)626-1531 Cell: (814)931-0060