Data Frame Structure

During communication between the IndyDCP server and client, data exchanged consists of a 52-byte header, a 4-byte command, and up to 200 bytes of data, collectively defined as a data frame. The data frame requested by the client to the server is called a request frame, while the data frame sent from the server in response to the request is called a response frame. The response frame is further categorized into an ACK (Acknowledgement) response frame, received upon a successful request, and a NAK (Negative Acknowledgement) response frame, received upon a failed request.

Header	Command	Data
52 bytes	4 bytes	0 ~ 200 bytes

Header Format

The below table is a detailed description of the header section within the data frame:

Item	Size (byte)	Detail
Robot Name	20	Client $\rightarrow$ Server : "NRMK-[Robot Name]" (ASCII string) Server $\rightarrow$ Client : "NRMK-[Robot Name]" (ASCII string) Reference: Empty space is filled with NULL values. Example: "NRMK-Indy7" (ASCII Code: 0x4E 0x52 0x4D 0x4B 0x2D 0x49 0x6E 0x64 0x79 0x52 0x50 0x00 ...)
Robot Version	12	Client $\rightarrow$ Server : NULL Server $\rightarrow$ Client : IndyFramework Version (ASCII string) Example: 3.2.0 (ASCII Code: 0x32 0x2E 0x30 0x2E 0x33 0x00 ...)
STEP Info	1	Client $\rightarrow$ Server : Not Use (0x00) Server $\rightarrow$ Client : STEP HW Version (1-byte) Example: STEP 1,2,3 $\rightarrow$ 0x01, 0x02, 0x03
Source of Frame (SoF)	1	Client $\rightarrow$ Server : 0x34 Server $\rightarrow$ Client : 0x12
Invoke ID	4	ID to differentiate between frames (Response frames for requests are sent back with the same ID as the request)
Data Length	4	Data length of data area (unit: bytes, 0~200)
Reserved	10	Reserved field 4byte use robot state

Reserved field and Robot State

The first 4 bytes of the reserved field, out of the total 10 bytes in the response frame header, contain the robot's status information. This allows receiving the robot's status without making specific command requests, enabling periodic updates of the robot's status with every response to a request. To retrieve only the robot's status, you can use the command 0 (check) in the command list to exchange headers and periodically monitor the robot's status. The robot states mapped to each bit (1 to 32) are detailed in the table below [table4].

Bit Num	State	Detail
1	Is Robot Running	The robot is in running state.
2	Is Robot Ready	The robot is in a controllable state (all servos are On and initialization is complete)
3	Is Emergency Stopped	The robot is in Emergency state
4	Is Collided	The robot is in Collision state
5	Is Error State	The robot is in Error state
6	Is Busy	The robot is in Motion state (Motion in progress)
7	Is Move Finished	The robot is in the motion finished state
8	Is Home	The robot is in the Home Position state
9	Is Zero	The robot is in the Zero Position state
10	Is In Resetting	The robot is in resetting state
25	Is Direct Teaching Mode	The robot is in direct teaching mode
26	Is Teaching Mode	The robot is in teaching mode (manual teach, jogging, etc.)
27	Is Program Running	The robot program is in execution state (including running and paused)
28	Is Program Paused	The robot program is in paused state
29	Is Conty Connected	The robot is Connected to Conty

Command and Data

The format of the header is identical for request frames, ACK response frames, and NAK response frames as follows:.

Robot Name

Robot Version

Step Info

SoF

Invoke ID

Data Length

Reserved

Request Frame (IndyDCP Client → Server)

Header	Command	Data
Common 52 byte	Command ID 4 bytes	Depending on the command, the format and length vary 0 ~ 200 bytes

ACK Response Frame (IndyDCP Server → Client, Upon successful request execution)

Header	Command	Data
Common 52 byte	Command ID, same as the request frame 4 bytes	Depending on the command, the format and length vary 0 ~ 200 bytes

reference

The basic structure of request frames and response frames is identical (maximum 256 Byte frame).

NAK Response Frame (IndyDCP Server → Client, Upon failed request execution)

Header	Error	Error code
Common 52 byte	Instead of a command, it has a value of 9999 indicating an error status 4 bytes Intiger	It carries an error code instead of data 4 bytes Intiger

reference

1) Hexadecimal data within the frame is represented with the prefix '0x', such as 0xA4, 0x23.
2) String data such as Robot Name or Robot Version is represented as ASCII strings.
3) Values (or data values) for all items, except for a few, are represented in binary format. Boolean is 1 byte, Integer is 4 bytes, and floating-point number is an 8-byte floating point (double).