IbaLink-SM-128V-i-2O VMEbus interface board

5.5 Process I/O Mode

Scenario: Use SM128V as a remote I/O expansion module for VME PLC and connect it to ibaPADU-8 or ibaNet750-BM series field I/O devices.

Topology: Each fiber output channel can connect up to 8 output type I/O devices (such as ibaPADU-8-O). Supports only daisy chain structure.

Advantage: Extend the I/O capability of the VME system to the field and achieve distributed control.

VMEbus interface and address space mapping

Understanding the VME address space of SM128V is crucial for PLC programming. The board occupies 256 kByte of memory and its internal structure is divided into multiple functional areas.

Hardware control area (0000H-003FH): includes hardware reset registers, etc. Writing 5AH to address 08H can trigger a hardware reset.

Version Information Area (0040H-007FH): Stores hardware, firmware, and standard version information, such as "SM128-VME".

Status indicator area (0080H-00FFH): Contains a Life counter that increments every 0.8 seconds to monitor the health status of the board.

Input data area (received message):

Binary input (2400H): 64 numerical values, stored in bit packed form in 8 bytes.

Analog input (3000H): 64 analog input values, each value occupies 4 bytes (IEEE floating point or integer), and the byte order is determined by DIP switches.

Input status (1800H): Indicates the status of the input channel, such as whether a message has been received, data format, etc.

Output data area (message to be sent):

Analog output (3800H channel 1, 3900H channel 2): 64 analog output values.

Binary output (3E00H channel 1, 3F00H channel 2): 64 digital output values, stored in the form of DWOs, with each LSB being valid. At addresses 2420H and 2428H, binary outputs in bit packing form are also provided, and the results of the two regions will be sent after an OR operation.