Lexicon MC-12 User Guide

Lexicon
MC-12 Serial Communications Protocol

Printed on: 07/13/05

The data value transmitted is dependent on the ParamType, as described above. The
CurrentValue is always packed starting at the CurrentValue [0] byte in the packet. For
multi-byte data, the values are packed LSB first(CurrentValue [0]) to MSB(CurrentValue
[0+(num bytes-1)]). For example: Setting a given signed 16 bit parameter to a value of -
300 the data array would be packed as follows:

Data[0] = 0xd4

Data[1] = 0xfe

Data[2 - 13] = don't care.

If a parameter's current value is a signed 16 bit parameter with a value of -3 the data
array would be packed as follows:

Data[0] = 0xfd

Data[1] = 0xff

Data[2 - 13] = don't care.

All signed values are in the 2's compliment format.

Max Value:

This is a 16 bit value representing the maximum value for a parameter. Parameter values
exceeding the maximum will be limited to the maximum. This may be a signed or
unsigned value depending on the Parameter Type.

Min Value:

This is a 16 bit value representing the minimum value for a parameter. Parameter values
exceeding the minimum will be limited to the minimum. . This may be a signed or
unsigned value depending on the Parameter Type.

Parameter Path:

This is a zero terminated ASCII character string describing the parameter's name and
path in the units parameter tree structure.

Read Only:
Data

Type:

Boolean

TRUE:

Parameter is read only

FALSE:

Parameter

writeable

7.3.37 MC-12 Set Parameter Value by Id (MC-12)

MC-12 Set Parameter by Id command sets the parameter value equal to the value sent in the command
packet and then runs the appropriate functional changes associated with changing the given parameter.

7.3.37.1 Command Packet Description

Application Header:

Command MC_CMD_SET_SYS_PARAM_VALUE_BY_ID 0x36
Data Count 24

0x18

Application Data:

Data[0] ParamId(LSB)

Data[1] ParamId(MSB)

Data[2] ParamType

Data[3-23] Value[0 -20]

nn nn nn…

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