Communication Alarms and Trips

Introduction

Communication alarms and trips are managed in a standard way, like any other types of alarms and trips.

The presence of a trip is signaled by various indicators:

State of the LEDs:
- On LTMR Ethernet controllers: 3 LEDs are dedicated to communication, 1 STS LED and 2 LK/ACT LEDs, one for each network port connector.
- On LTMR Modbus controllers: 1 LED is dedicated to communication, PLC Comm.
- On LTMR PROFIBUS DP controllers: 1 LED is dedicated to communication, BF.
- On LTMR CANopen controllers: 1 LED is dedicated to communication, Status.
- On LTMR DeviceNet controllers: 1 LED is dedicated to communication, MNS.
State of the output relays
Alarm
Message(s) displayed on HMI screen
Presence of an exception code (such as a report from the PLC)

PLC Communication Loss

A communication loss is managed like any other trip.

The LTMR controller monitors the communication with the PLC. Using an adjustable network idle time (timeout), the LTMR controller watchdog function can report a network loss (firmware watchdog).

NOTE: This timeout is not defined in the LTMR PROFIBUS DP controller but at the PROFIBUS DP primary level. If the PROFIBUS DP primary allows the modification of this timeout, then, its value must be transmitted by the primary to the LTMR PROFIBUS DP controller.

In the event of a network loss, the LTMR controller can be configured to take certain actions. These depend on the control mode that the LTMR controller was operating in prior to the network loss.

If PLC-LTMR controller communication is lost while the LTMR controller is in network control mode, the LTMR controller enters the fallback state. If PLC- LTMR controller communication is lost while the LTMR controller is in local control mode, and then the control mode is changed to network control, the LTMR controller enters the fallback state.

If PLC-LTMR controller communication is restored while the control mode is set to network control, the LTMR controller exits the fallback state. If the control mode is changed to local control, the LTMR exits from the fallback state, regardless of the state of PLC-controller communications.

The table below defines the available actions that the LTMR controller can take during a communication loss that the user can select when configuring the LTMR controller.

Network communication loss actions:

LTMR Controller Output Control Mode Prior to Network Loss	Available LTMR Actions After PLC-LTMR Controller Network Loss
Terminal Strip and HMI control	Trip and Alarm control possibilities: Signal nothing Activate an alarm Activate a trip Activate a trip and alarm
Network control	Trip and Alarm control possibilities: Signal nothing Activate an alarm Activate a trip Activate a trip and alarm The behavior of the LO1 and LO2 relays depends on the motor controller mode and on the fallback strategy chosen

LTMR Controller Output Control Mode Prior to Network Loss

Available LTMR Actions After PLC-LTMR Controller Network Loss

Terminal Strip and HMI control

Trip and Alarm control possibilities:

Signal nothing
Activate an alarm
Activate a trip
Activate a trip and alarm

Network control

Trip and Alarm control possibilities:

Signal nothing
Activate an alarm
Activate a trip
Activate a trip and alarm
The behavior of the LO1 and LO2 relays depends on the motor controller mode and on the fallback strategy chosen

HMI Communication Loss

The LTMR controller monitors the communication with any approved HMI device. Using a fixed network idle time (timeout), the LTMR controller watchdog function can report a network loss. In the event of a communication loss, the LTMR controller can be configured to take certain actions. These depend on the control mode that the LTMR controller was operating in prior to the communication loss.

If HMI-controller communication is lost while the LTMR controller is in HMI control mode, the LTMR controller enters the fallback state. If HMI-LTMR controller communication is lost while the LTMR controller is not in HMI control mode, and then the control mode is changed to HMI control, the LTMR controller enters the fallback state.

If HMI-controller communication is restored while the control mode is set to HMI control, the LTMR exits from the fallback state. If the control mode is changed to Terminal Strip or Network control, the LTMR exits from the fallback state, regardless of the state of HMI-controller communications.

The following table defines the available actions that the LTMR controller may take during a communication loss. Select one of these actions when configuring the LTMR controller.

LTMR Controller Output Control Mode Prior to HMI Loss	Available LTMR Controller Actions After HMI-LTMR Controller HMI Loss
Terminal Strip and network control	Trip and Alarm control possibilities: Signal nothing Activate an alarm Activate a trip Activate a trip and alarm
HMI control	Trip and Alarm control possibilities: Signal nothing Activate an alarm Activate a trip Activate a trip and alarm The behavior of the LO1 and LO2 relays depends on the motor controller mode and on the fallback strategy chosen

LTMR Controller Output Control Mode Prior to HMI Loss

Available LTMR Controller Actions After HMI-LTMR Controller HMI Loss

Terminal Strip and network control

Trip and Alarm control possibilities:

Signal nothing
Activate an alarm
Activate a trip
Activate a trip and alarm

HMI control

Trip and Alarm control possibilities:

Signal nothing
Activate an alarm
Activate a trip
Activate a trip and alarm
The behavior of the LO1 and LO2 relays depends on the motor controller mode and on the fallback strategy chosen

NOTE: For more information about a communication loss and the fallback strategy, refer to the Fallback Condition portion of the topic describing Communication Loss in TeSys T LTMR Motor Management Controller User Guide.