Connections Map

The Modbus protocol supports various blocks types. Each block type can be either an input block or an output block. Input blocks contain write-only registers and are used by the Modbus client to send commands such as starting or stopping a scan. Output blocks contain read-only registers and are used to store various types information, such as control, system, and sensor group state data as well as scan output data.

The starting address location of each block within the Modbus register map may be assigned using the GoPxL web interface.

The register address of a specific field within a block is equal to the block's address plus the field's address offset. For example, the command identifier in the Control Input block has an address offset equal to 1. If the Control Input block is located at register address 100, the command identifier value is located at register address 101.

Supported Block Types

The block types supported by the Modbus protocol are listed in the table below. The size field indicates the number of registers that each block type requires.

Supported Block Types
Block Description	Supported Block Type	Read or Write only?	Size (number of Modbus registers)	Description
Control Input	"ControlInput"	WO	66	Command message set by the Modbus client.
Control Output	"ControlOutput"	RO	2	Result data corresponding to a command that was written to the Control Input block.
System State	"System"	RO	72	Information about the LMI device.
Sensor Group State	"Scanner"	RO	10	Information about a specific sensor group.
Stamp	"Stamp"	RO	17	Stamp message information.
Measurement	"Measurement"	RO	3	Measurement data of a scan output measurement data message.

Control Input

The input of the Control Input block contains the fields described below:

Control Input Fields
Field	Type	Address offset	Description
Command Sequence Number	16u	0	The command sequence number is set by the external client to uniquely identify a command request. This number is sent back in the Control Output. This is an optional field but is recommended that Modbus clients use this to help the clients correlate the Command Status in the Control Output with a specific command request in Control Input.
Command Identifier	16u	1	Identifies the requested action from the external client. Supported actions: 0 = No Command 1 = Start Scanning 2 = Stop Scanning 3 = Align Sensor Group 4 = Clear Alignment 5 = Load Job File 6 = Software Trigger 7 = Buffer Advance
Command Arguments	16u	2	Arguments for commands that require arguments. For the Load Job File command, the command arguments will contain the NULL terminated job file name. The job file name must not include the job file extension. The job extension is automatically appended by the Modbus server. This field takes up a maximum of 64 registers.
Reserved	16u	66	Not used. This field takes up 57 registers.

Control Output

The output of the Control Output block contains the fields described below:

Control Output Fields
Field	Type	Address offset	Description
Command Sequence Number	16u	0	The command sequence number received from the client in the Control Input.
Command Status	16u	1	Status of the command, referenced by the Command Sequence Number. 0 = No Command Received 1 = In Progress 2 = Success 3 = Fail This field takes up 1 register.

System State

The output of the System State block contains the fields described below:

System State Fields
Field	Type	Address offset	Description
System Uptime	64u	0	Amount of time the application has been running, in seconds.
System State	16u	4	Whether system is running or not. 0 = System is stopped 1 = System is running
Current Job File Name Length	16u	5	Number of characters in the current job file name.
Current Job File Name	16u	6	Name of the job file currently loaded into the system, including extension. Maximum length of job file name is 64 characters. Each register contains a single character. Job file name is not null terminated.
Buffer Count	16u	70	The current amount of buffered scan output data when buffering is enabled.
Buffer Overflow	16u	71	A value of 0 indicates that no overflow has occurred. A value of 1 indicates that overflow occurred and data is being lost. This field takes up 1 register.

Sensor Group State

The output of the Sensor Group State block contains the fields described below:

Sensor Group State Fields
Field	Type	Address offset	Description
Current Encoder Position	64s	0	The current encoder position.
Current Sync Time	64u	4	Current time of the clock used to stamp all scan output messages, in microseconds.
Alignment State	16u	8	Indicates whether all devices under the sensor group are aligned (that is, devices in the sensor group all have a non-identity transform matrix). 0 = Not Aligned 1 = Aligned 2 = Aligning
Laser Enabled	16u	9	Whether one or more devices under a scanner has its laser enabled to be able to turn on. 0 = All devices' lasers are disabled and cannot turn on 1 = One or more devices' lasers can be turned on This field takes up 1 register.

Stamp

The output of the Stamp block contains the fields described below:

Stamp Fields
Field	Type	Address offset	Description
Z Position	64s	0	Encoder position at time of last index pulse of last frame.
Encoder Position	64s	4	Encoder position of last frame when the image data was scanned/taken.
Time	64u	8	Time stamp, in microseconds, of last frame.
Frame Index	64u	12	The frame number of the last frame. This field takes up 4 registers.
Digital Input States	16u	16	Digital input states of last frame. Bit 0: State of digital input 1 on master or sensor Bit 1: State of digital input 2 on master or sensor

Measurement

The output of the Measurement Block contains the fields described below:

Measurement Fields
Field	Type	Address offset	Description
Value	32s	0	Measurement value. This value is the actual measurement value multiplied by 1000. If the measurement value is invalid, the first register of the measurement value is set to 0x80000000. This means the first register of the measurement value is set to 0x8000 and the second register value is 0x0000.
Decision	16u	2	Measurement decision. Bit 0: 0 = Fail 1 = Pass Bit 1: 0 = Decision value is valid 1 = Decision value is invalid This field takes up 1 register.