Modes Of Operation; Monitor Mode; Scan Bus Mode; 1-On-1 Mode - Johnson Controls MS-FIT100-0 User Manual

see the devices directly connected on the FC bus, but not the SA bus. Conversely, when the FIT is
connected to the SA bus, it can only see the devices on the FC bus, but not the SA bus
It is best to connect the FIT tool to the bus and then power it up. Assuming communication is
occurring, the FIT first has to determine the baud rate of the communication signal before it can
read the communication messages. If the FIT is powered before it is connected to the bus, the
mechanical connection causes the bus voltage to be unstable for a time, which can cause the FIT
to mistake the proper baud rate. The occurrence of this issue is unlikely, but it can occur. When no
communication is occurring (the bus is in a fixed idle state), the FIT initially displays Offline.

Modes of Operation

The FIT has three main modes of operation to help troubleshoot MS/TP buses: Monitor mode, Scan
Bus mode, and 1-ON-1 mode.

Monitor Mode

The Monitor mode allows the FIT to see devices that are connected to and communicating on
the bus. If the health bars appear on the display when the FIT is connected to the bus, then
communications are occurring. Enter the Monitor mode by pressing the Enter Key or by scrolling
to the Monitor menu. The Monitor mode only listens to the communications occurring on the bus,
does not interact with the communications, and therefore does not affect the operation of the bus.
The Monitor mode is recommended to use first if communications are already occurring on the
FIT Menu Monitor Menu.
bus. For more information, see the and

Scan Bus Mode

The Scan Bus mode interacts with the communications on the bus because it reads the attributes
of the controllers communicating on the bus. If no communications are occurring on the bus, the
Scan Bus mode starts communications to all controllers on the bus. The Scan Bus mode is helpful
when there is not an active supervisory controller connected to the bus since it is the supervisory
controller that usually starts the communications due to fixed address. The Scan Bus mode is used
to read the EOL termination attribute of the controller. The EOL termination attribute is limited to
Johnson Controls manufactured products that have a built-in EOL switch. The location of other EOL
Proper EOL Termination, FIT
devices, such as the MS-BACEOL-0 or jumpers, are not detected. See
Menu Scan Bus Menu
and for more information.

1-ON-1 Mode

The 1-ON-1 mode is used to test a single controller that is disconnected from the network with the
FIT connected to the FC Bus. In the 1-ON-1 mode, the FIT supplies the proper EOL termination to
test the communications of the device. In the 1-ON-1 mode, all of the attributes of the controller
can also be read, such as Model name, Firmware revision, EOL termination switch, and other
attributes. The 1-ON-1 mode is used to verify the operation of any single controller that does
not communicate on the bus. It is used to help determine if a Johnson Controls manufactured
controller is defective.
The FIT only validates MS/TP controllers and devices that are hardwired to a FC/SA Bus. Wireless
devices are not currently supported other than the 1-ON-1 mode at the controller's SAB port.
FIT Menu 1-ON-1 Menu.
For more information, see and

Battery Usage

The FIT is operated from two AA Alkaline battery cells. When operated with the LCD backlight
turned off, the FIT can operate for approximately 50 continuous hours. Continuous operation with
the LCD backlight on is approximately 20 hours.
MS-FIT100-0 Field Inspection Tool User Guide 5