Creating Large Curves using the Curve Add Command

Large curves are curves that are too large to be written at once in their entirety to the variable table. Creating large curves via the Variable Table involves writing the curve data in parts to the variable table and issuing the Curve Add (82) command after each part until all the curve data has been written. This topic describes how to add curves in parts. Only one partial curve download can be in progress at a time.

See the Curve Storage Capacity topic for limits on how many curves can be added to the RMC.

These formats are based on the single curve formats (see the Curve Data Formats topic), but with modifications to support downloading in parts. The following chart summarizes the partial curve formats:

Offset

Description

Status

The value of this register when passed to the Curve Add (82) command is ignored, but after the Curve Add (82) command is issued, the value of this register will be controlled by the RMC and indicates the status of processing the curve. The user should monitor this to determine when the command is finished processing the curve data. The following values are defined:

(0) Processing Not Started

By convention the user may want to set this register to this value before issuing the command. This is not strictly necessary, but otherwise the user must make sure not to check this register until after the command has been received.
(1) Processing

Once the command has been received, the Status will immediately be set to Processing. While in this state the command is currently using the Curve Data structure, and the curve is not ready for interpolation.
(2) Part Complete

For all but the last part in a partial curve download, once the command has completed processing the part, this status value will be used. The user can now write down the next part of the curve.
(3) Curve Ready

Once the curve data has been processed, and the entire curve is ready for interpolation, the status will be set to this value. Notice that this value will be used for only the final part for curves submitted in parts. Therefore, for the last part of a curve, the Part Complete (2) state won't be used—the status will change directly from Processing (1) to Curve Ready (3).
(10+) Error

Values of 10 and above will indicate various errors. When an error code is set in this register, it indicates that the command is done trying to process this Curve Data, but the curve was not submitted to the curve store. See Curve Status Error Codes for a list of possible error values.

It is good practice to set this value to zero when writing the data.

Format

One of the following:

20 - Evenly-Spaced Points

21 - Variable-Spaced Points

22 - Advanced Points

This value must be the same for each part.

PartOffset

Offset of this part of the whole curve (in registers). This value will change for each part.

PartLength

Number of curve data registers in this part, not including the 5 header registers with offsets 0-4. Typically, this value is the same for each part except the last.

TotalLength

Total length of curve data (sum of all parts). This is the length of the corresponding single curve format, but with the Status and Format registers stripped off. This value must be the same for each part.

5..5+(L-1)

PartData

Segment of the curve data in the respective single curve format. The curve data here consists of the corresponding single curve format, but with the Status and Format registers stripped off.

To download a large curve to the RMC, repeat the following procedure until all the data has been downloaded:

Registers 0 - 4 of the Partial Curve Format listed above must always be included in each write. The actual data of the curve is included in registers 5 and on. The data in the registers 5 and on is the data of the corresponding single curve format, but with the Status and Format registers stripped off.

The value 2 indicates that the part was successfully added.
The value 3 indicates that the entire curve has now been successfully added.

Suppose that the user wants to download a 2500-point curve through a block of 512 consecutive variables starting at %MD58.0 (Variable #512). The user decides to use the evenly-spaced format, and interpolation option of zero (0) for Zero-Velocity Endpoints, initial X0 of 0, and an X interval of 0.1.

Since the user chose the Evenly-Spaced Points format, the curve data itself will require a total of 2504 registers, consisting of the items below. Notice that this is the Single Curve Evenly-Spaced Points format, but with the Status and Format registers stripped off.

The Variable Table area the user decided to use for the curve parts is 512 registers in length, which means the user can write up to 512 registers each time. The header for the Partial Curve format has 5 registers, which must be included in each part. Therefore, the user can write up to 507 Curve Data registers per part.

Here is the sequence of parts that would add this curve to the curve store, with each part being written and then submitted with a Curve Add (82) command:

The user would send this curve to the RMC by completing the following sequences of writes to the Variable Table:

Note: This is very tedious to do directly from RMCTools, but you may need to when you are first trying it.

*This number includes the four parameters and the number of points in this curve.

After writing part #1 and issuing the Curve Add command, the user should wait for the Curve Status at Variable 512 to become 2 (if you are looking in RMCTools, make sure to look in the Monitor tab of the Variable Table Editor), indicating that the RMC has completed processing the part.

After writing part #2 and issuing the Curve Add command, the user should wait for the Curve Status at Variable 512 to become 2 (if you are looking in RMCTools, make sure to look in the Monitor tab of the Variable Table Editor), indicating that the RMC has completed processing the part.

After writing part #3 and issuing the Curve Add command, the user should wait for the Curve Status at Variable 512 to become 2 (if you are looking in RMCTools, make sure to look in the Monitor tab of the Variable Table Editor), indicating that the RMC has completed processing the part.

After writing part #4 and issuing the Curve Add command, the user should wait for the Curve Status at Variable 512 to become 2 (if you are looking in RMCTools, make sure to look in the Monitor tab of the Variable Table Editor), indicating that the RMC has completed processing the part.

After writing part #5 and issuing the Curve Add command, the user should wait for the Curve Status at Variable 512 to become 3 (if you are looking in RMCTools, make sure to look in the Monitor tab of the Variable Table Editor), indicating that the RMC has completed processing the curve. Notice that the curve data point numbering begins with 0, and therefore 2499 is the last point of the 2500-point curve.

Curve Data
Offset	Data Item
0	Point Count
1	Interpolation Options
2	X0
3	X interval
4	Y0
5	Y1
:	:
2503	Y2499

Variable	Data	Description	Curve Data Offset
512	0	Status = 0	-
513	20	Format = 20	-
514	0	Part Offset = 0	-
515	507	Part Length = 507*	-
516	2504	Total Length = 2504	-
517	2500	Point Count = 2500	0
518	0	Interpolation Options = 0	1
519	0	X0 = 0	2
520	0.1	X interval = 0.1	3
521	Y0	Y0	4
522	Y1	Y1	5
:	:	:	:
1023	Y502	Y502	506

Variable	Data	Description	Curve Data Offset
512	0	Status = 0	-
513	20	Format = 20	-
514	507	Part Offset = 507	-
515	507	Part Length = 507	-
516	2504	Total Length = 2504	-
517	Y503	Y503	507
:	:	:	:
1023	Y1009	Y1009	1013

Variable	Data	Description	Curve Data Offset
512	0	Status = 0	-
513	20	Format = 20	-
514	1014	Part Offset = 1014	-
515	507	Part Length = 507	-
516	2504	Total Length = 2504	-
517	Y1010	Y1010	1014
:	:	:	:
1023	Y1516	Y1516	1520

Variable	Data	Description	Curve Data Offset
512	0	Status = 0	-
513	20	Format = 20	-
514	1521	Part Offset = 1521	-
515	507	Part Length = 507	-
516	2504	Total Length = 2504	-
517	Y1517	Y1517	1521
:	:	:	:
1023	Y2023	Y2023	2027

Offset	Register	Description
0	Status	The value of this register when passed to the Curve Add (82) command is ignored, but after the Curve Add (82) command is issued, the value of this register will be controlled by the RMC and indicates the status of processing the curve. The user should monitor this to determine when the command is finished processing the curve data. The following values are defined: (0) Processing Not Started By convention the user may want to set this register to this value before issuing the command. This is not strictly necessary, but otherwise the user must make sure not to check this register until after the command has been received. (1) Processing Once the command has been received, the Status will immediately be set to Processing. While in this state the command is currently using the Curve Data structure, and the curve is not ready for interpolation. (2) Part Complete For all but the last part in a partial curve download, once the command has completed processing the part, this status value will be used. The user can now write down the next part of the curve. (3) Curve Ready Once the curve data has been processed, and the entire curve is ready for interpolation, the status will be set to this value. Notice that this value will be used for only the final part for curves submitted in parts. Therefore, for the last part of a curve, the Part Complete (2) state won't be used—the status will change directly from Processing (1) to Curve Ready (3). (10+) Error Values of 10 and above will indicate various errors. When an error code is set in this register, it indicates that the command is done trying to process this Curve Data, but the curve was not submitted to the curve store. See Curve Status Error Codes for a list of possible error values. It is good practice to set this value to zero when writing the data.
1	Format	One of the following: 20 - Evenly-Spaced Points 21 - Variable-Spaced Points 22 - Advanced Points This value must be the same for each part.
2	PartOffset	Offset of this part of the whole curve (in registers). This value will change for each part.
3	PartLength	Number of curve data registers in this part, not including the 5 header registers with offsets 0-4. Typically, this value is the same for each part except the last.
4	TotalLength	Total length of curve data (sum of all parts). This is the length of the corresponding single curve format, but with the Status and Format registers stripped off. This value must be the same for each part.
5..5+(L-1)	PartData	Segment of the curve data in the respective single curve format. The curve data here consists of the corresponding single curve format, but with the Status and Format registers stripped off.

Part	Address	Number Regs written to in Variable Table	PartOffset	PartLength	TotalLength
#1	%MD58.0	512	0	507	2504
#2	%MD58.0	512	507	507	2504
#3	%MD58.0	512	1014	507	2504
#4	%MD58.0	512	1521	507	2504
#5	%MD58.0	481	2028	476	2504