JMRI: Monitor Maple Traffic
Author: Bob Jacobsen
Keywords: JMRI help monitor maple traffic message packet

## Monitor Maple Traffic

This window allows you to monitor communication between your Maple panels and your computer, so you can see what is happening as JMRI sends information to and receives information from your Maple System. You can save this information to a log file for troubleshooting purposes.

Background Information: On Maple, the coil bits in the Maple HMI's are used to communicate with JMRI. In this Maple-to-JMRI implementation, all panels use the same address space and have exactly the same input and output bit assignments. The first 1000 coil bits are reserved for configuration as Sensors. Sensors are referred to as "Input Bits" and are used to set JMRI Sensors according to status bits in your Maple HMI panels. Therefore, Sensors pass information from configured HMI panels to JMRI. The next 8000 bits are reserved for assignment as "Output Bits" and are used to send the current settings of Turnouts and Lights to the Maple Panels.

Maple communications work by polling. Each panel is polled separately, and the results of the polls are ORed together to set Sensors. Therefore if a Sensor is ACTIVE (Maple "1") in any panel, it is set ACTIVE. If a Sensor is INACTIVE (Maple "0") in all configured panels, then it is set INACTIVE. The panels are polled in the order that they are configured. Note: The Maple poll command only allows a maximum of 99 bits to be read with each poll command, so if more than 99 input bits are configured, you will see multiple poll commands for each panel.

After all panels have been polled, the status of output bits is sent to the panels. Output bits are sent in "Broadcast Mode" so all panels can receive the bits at the same time. Broadcast Mode is indicated by an HMI Station Address of "0". Output bits begin with HMI coil bit address of "1001". All configured output bits are sent, regardless of if the bit is assigned or not. Note: The Maple write command only allows a maximum of 99 bits to be written with each transmit command, so if more than 99 output bits are configured, you will see multiple transmit commands, with starting addresses increasing by 99 in each.

For more information on the various controls and options at the bottom of this window, please see the Communications Monitor Window page.