Nidec H300 - Internal Float Values (Used to Access Specified Drive Parameters); Internal Float Value Points; Internal Float Value Status Byte; Attributes Supported for Internal Float Values

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HVAC Drive H300 191
Issue Number: 3
The "Current State" bit reflects the value of the drive's binary output. Any of the Binary Output points may be overridden. However, only the first two
are read-write and can thus update the bit value in the drive.
These bits are re-evaluated whenever the status or current values of the Binary Output Point are queried. They are also re-evaluated whenever a
"Poll without Acknowledge" command is received and this point's "COS-enable" bit is set.
The Binary Output Status attribute cannot be written to; the only permissible operation is "Read" or "Override".
10.5.6 Internal Float Values (used to access specified drive parameters)
Internal float points are not associated with any drive parameter; rather they are resident in the Metasys controller. The three defined Internal Float
points are given a specific behaviour that allows the Metasys user to manipulate them to gain access to any drive parameter. Use Attribute number 1
or 2 to read the Status byte and the Internal Float value for each point.
Table 10-42 Internal float value points
Object Status
The Internal Float Object Status byte has the following format:
Table 10-43 Internal float value status byte
The "Reliable/Unreliable" bit will be set if the drive has tripped.
The Internal Float Points do not participate in COS polling operations
Table 10-44 Attributes supported for Internal Float Values
The Internal Float Status attribute cannot be written to; the only permissible operation is "Read".
Writing to the Current Value of Internal Float, Point 1 changes the value on the drive if the parameter exists and the Internal Float, Point 2 Command
Code is 1.
Current Value
The current value of each point is returned as a 32-bit (4 byte) IEEE floating point number.
Using the Internal Float Points to Access any Drive Parameter
A very specific sequence must be followed to use the Internal Float Points to gain access to any drive parameter.
Read a drive parameter
• Write the desired menu and parameter number (mm.ppp) to Internal Float, Point 0
• Write the "read" command code (2) to Internal Float, Point 2
• Read the mm.ppp Internal Float, Point 0 to ensure that it has been cleared to zero indicating data is ready
• Read the Internal Float, Point 1 which will return the floating point value of the requested parameter
Write a drive parameter
• Write the desired menu and parameter number (mm.ppp) to Internal Float, Point 0
• Write the "write" command code (1) to Internal Float, Point 2
• Write the new parameter value to Internal Float, Point 1
Internal Integer Values and Internal Byte Values. While the Metasys protocol provides for Internal Integer Points and Internal Byte Points, Control
Techniques has not implemented any functionality for them. Attempts to access Internal Integer and Internal Byte Points will result in an error
message.
Point Parameter Description Access Notes
0 Internal Float 0
Menu/Parameter
(specified as a float where 1.25 is parameter #1.25)
RW
Reading returns the status and Menu/
Parameter as a float
1 Internal Float 1
Value (specified as a float)
e.g. 1.0 = 1 for bit parameters, 62.5 for decimal parameters.
RW
Reading returns the status and the Value
as a float
2 Internal Float 2
Read/Write Command Code
0 = Idle, 1 = Write, 2 = Read
RW
Reading returns the status and the
Command Code as a float
Description Not used Not used Not used Not used Not used Not used Not used
Reliable /
Unreliable
Bit76543210
Attribute Name Commands
1 Object Status Read
2 Current Value Read, Override
NOTE