i-MARKInstallation and Hardware Manual
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4.3.3
Operation Mode—Continuous/host only
Note: The default operation mode is “continuous”, as most i-MARK installations will be autonomous.
In the continuous operation mode the i-MARK will transmit the LF telegram based on the slot
configuration and synchronized time (refer to the section 4.3.5).
In cases where an application may need to have full control over when the i-MARK transmits the LF
telegram the i-MARK can be switched into host only mode. The host is then responsible for telling the
i-MARK when to transmit a LF telegram.
4.3.4
Operation Mode—Slave/master
Note: This default operation mode is master.
The recommended configuration is to have a host present on the RS422 bus. This allows for the
retrieval of device status information and detection of device failure in real time. In this application,
the host will be the master and must send the synchronization messages to the i-MARK and all of the
i-MARKs must be configured as slaves.
In applications where an i-HUB or host is not required on the bus, but synchronization needs to occur,
a single i-MARK on the bus can be configured as a master. An i-MARK which is configured as a master
must be the first device in the bus hierarchy. When configured as a master it is only able to
communicate with devices which are connected off of its slave port. As such, all other i-MARKs
connected must be configured as a slave device. This single master on the bus will be in charge of
broadcasting the synchronization messages on the bus.
In slave mode the position marker will only transmit the LF telegram based on the synchronization
scheme or host request depending in the operating mode.
In master mode the device will additionally transmit synchronization telegrams and this independently
on the operating mode it is configured in.
4.3.5
Synchronization Mechanism
Note: This setting is only of importance if several i-MARKs are in close proximity to each other. The
default factory setting is that all time slots are used.
The synchronization mechanism goal is to avoid having multiple i-MARKs in overlapped transmit areas
transmit at the same time and disturb each other.
For this task, all the devices must be synchronized, and follow the synchronization mechanism
described below.
The modules synchronization is done by having 1 master device (i-HUB or Host application or a
i-MARK in master mode) to broadcast on the bus a synchronization telegram on a regular interval.
Default configuration is, that a device send in each of the 12 slots.
The time is divided in 12 slots of 20 milliseconds each.
