LF: MODBUS Aperiodic Functions (Ladder Triggered)

These operations allow you to run MODBUS operations via Ladder function. MODBUS Periodic operations answer most needs; Aperiodic functions allow you to perform an operation that only needs to run once, such as starting a machine, or writing a speed value to a frequency converter.

You must not place an Aperiodic function on the bus bar, or anywhere it will be continuously activated. Use a delay of 10-50 msec between requests.

MODBUS Aperiodic (InDirect)

Use this to trigger a single, specific operation of a MODBUS master, according to the operation ID number.

	Parameter Name	Purpose
A	Master	Links to a master's specific slave.
B	ID to Trigger	This is the ID# of the operation. You can provide a constant or a tag.
C	Status	The value indicates the status of the function: 0 - No error 1 - Function started 2 - Function in Progress -1 - Modbus Protocol Error The error code is stored in the Status operation of the operation linked to this function. The actual message that the code indicates is the Modbus protocol; check Modbus documentation. -2 - Initialization error -3 - Invalid event ID -4 - Invalid group ID -5 - Invalid data size -6 - Parameters error -7 - Configuration error For other negative status values, note the status code and contact support

MODBUS Aperiodic InDirect Group Trigger

Use this to trigger a group of operations, according to the group ID number.

	Parameter Name	Purpose
A	Master	Links to a master's specific slave.
B	Group ID to Trigger	This is the Group ID# n. You can provide a constant or a tag.
C	Status	The value indicates the status of the function: 0 - No error 1 - Function started 2 - Function in Progress -1 - Modbus Protocol Error The error code is stored in the Status operation of the operation linked to this function. The actual message that the code indicates is the Modbus protocol; check Modbus documentation. -2 - Initialization error -3 - Invalid event ID -4 - Invalid group ID -5 - Invalid data size -6 - Parameters error -7 - Configuration error For other negative status values, note the status code and contact support

MODBUS Aperiodic (Direct)

Use this to trigger a single, specific operation of a MODBUS master. Note that this function does not have a status indication, and is maintained for backwards compatibility with older applications.

	Parameter Name	Purpose
A	Event to Trigger	Links to a specific slave, and specific operation within the slave configuration.