RMA RouterBoard 751 series User Manual - Routerboot
6
Buttons and Jumpers
RouterOS reset jumper hole (on the bottom of case) – resets RouterOS software to defaults. Must
short circuit the metallic sides of the hole with a screwdriver and boot the device. Hold screwdriver in
place until RouterOS configuration is cleared.
RouterBOOT reset button (RES, front panel) has two functions:
o Hold this button during boot time until LED light starts flashing, release the button to reset
RouterOS configuration (same result as with RouterOS reset hole)
o Hold this button during boot time longer, until LED turns off, then release it to make the
RouterBOARD look for Netinstall servers.
Wireless device
RB751U includes a 2GHz 802.11b/g/n wireless device built in. It has PIF type antennas (2.5dBi) built into the
case, and one MMCX connector for an optional external antenna.
RB 751U has 3 built-in wireless antennas
Chain0
o one antenna for TX
o one antenna for RX
Chain1
o one antenna for TX/RX
o MMCX connector for external antenna
To enable the external MMCX connector, set „antenna mode: antenna-b” in RouterOS wireless settings, in the
HT tab of Winbox. Note: enabling the external antenna disables the built-in Chain1 antenna.
RouterBOOT
The RouterBOOT firmware (also referred as Bootloader here) provides the basic functionality to boot an
Operating System. It supports serial console via the onboard serial port at the boot time. The loader supports
booting from the onboard NAND device and from a network server (see the respective section for details on
this protocol).
Boot Loader Configuration
This device doesn’t come fitted with a serial port connector, so all Bootloader specific settings must be done in
RouterOS. See „RouterOS functions”
Boot Loader Upgrading
The boot loader is needed to initialize all the hardware and boot the system up.
The boot loader upgrading is possible from MikroTik RouterOS, from within the “/system routerboard” menu.
Updates are included with each RouterOS update. The procedure is described in the MikroTik RouterOS
manual:
http://wiki.mikrotik.com/wiki/Manual:Bootloader_upgrade
Primary Boot Loader
There are two boot loaders present on the NOR flash memory chip. Secondary is the main one, that is
executed by default. This is the one that can be upgraded. In case something goes wrong in the upgrade
process, or you have set some incorrect settings that render it unusable, you can load the Primary boot loader
by holding the Software Reset 1 button (S401), connecting the power, and then releasing the button/jumper.