MDEV-868-PRC datasheet(11/55 Pages) LINX

11 / 55 page

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Transceiver Operation

The transceiver has two roles: Initiating Unit (IU) that transmits control

messages and Responding Unit (RU) that receives control messages. If all

of the status lines are set as inputs, then the module is set as an IU only.

The module stays in a low power sleep mode until a status line goes high,

starting the Transmit Operation.

If all of the status lines are set as outputs, then the module is set as an RU

only. It stays in Receive Operation looking for a valid transmission from a

paired IU.

A module with both input and output status lines can operate as an IU

and an RU. The module idles in Receive Operation until either a valid

transmission is received or a status line input goes high, initiating the

Transmit operation.

When an input goes high, the transceiver captures the logic state of each

of the status lines. The line states are placed into a packet and transmitted

using the configured addressing mode, hop sequence and encryption key

(if enabled).

An associated RU receives the packet and sets its status line outputs

according to the received packet. It then stays synchronized with the IU

and updates the states of its outputs with every packet. Its outputs can be

connected to external circuitry that activates when the lines go high.

The RU can also send an acknowledgement back to the IU. If the ACK_EN

line is high when a valid control packet is received, the RU sends back an

acknowledgement. When the IU receives the acknowledgement, it raises its

ACK_OUT line. The ACK_EN line can be connected to ground to disable

acknowledgements, connected to the power supply to acknowledge

on receipt of the valid command or controlled by external circuitry to

acknowledge when an action has taken place.

The ACK_EN can be connected to an LED as an indication to the user or

used by the system in other ways, such as updating a display or being

used to deactivate an automated system.

Transmit Operation

When a status line input goes high, the module enters the Initiating Unit

role. In this role, the module captures the logic states of the status line

inputs and automatically creates a REMOTE_ACTIVATE packet. The packet

is transmitted every 140ms nominally (240ms max) for as long as a status

line input is held high. After each transmission, the module listens for a

REMOTE_CONFIRM reply from the RU. This continues for as long as any

status line input is high.

The REMOTE_CONFIRM packet contains two values. One indicates how

long the ACK_OUT line should go high on the IU (20ms by default) and the

other indicates if the IU should stay awake after the status line inputs go

low (go to sleep by default). The module activates the ACK_OUT line for as

long as instructed and loops back to check the status line inputs and send

another REMOTE_ACTIVATE packet.

When all status line inputs go low, the module transmits two REMOTE_

ACTIVATE packets indicating that all lines are low. If all status lines are

inputs, it then goes to sleep after 760ms unless a REMOTE_CONFIRM

packet is received instructing the IU to stay awake longer.

Receive Operation

When the module is awake and not in transmit operation, it is in receive

operation listening for valid packets. When a REMOTE_ACTIVATE packet

is received, the module enters the Responding Unit role and processes the

received status line states. It remains in the RU mode until 760ms elapses

without an incoming REMOTE_ACTIVATE message.

Unlatched status line outputs are set to match the corresponding bit state

in the received packet.

For latched outputs, the line changes state (off ª on or on ª off) whenever

the corresponding bit changes from 0 to 1. All other combinations of

the new and old status bit do not change the status line. This normally

changes the output state every time that the associated transmitter input

changes from 0 to 1.

If the ACK_EN line is high when a valid message is received, a REMOTE_

CONFIRM message is transmitted to the IU with values to set the ACK_

OUT high for 20ms and go to sleep after the default 760ms. These values

cannot be changed in the HumPRCTM Series, but a packet with different

values can be generated using the HumPROTM Series and a microcontroller.

MDEV-868-PRC Datasheet(PDF) 11 Page - Linx Technologies

MDEV-868-PRC Datasheet(HTML) 11 Page - Linx Technologies

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