SDMGeneric (Generic SDM Device)
The SDMGeneric instruction is used to send commands to an SDM device that is otherwise unsupported in the datalogger.
Syntax
SDMGeneric ( Dest, SDMAddress, CmdByte, NumValuesOut, Source, NumValuesIn, BytesPerValue, BigEndian, DelayByte )
Example
This example program shows the use of the SDMGeneric instruction to check for the OS Version and OS signature check for the SDM-SIO1A.
'Simple OS Version and OS sig check for the SDM-SIO1A
'Variables and constants for the version number and signature checking
Public Ver_Value As String * 25 'Holds version as text string
Public Sig_Value As String * 4 'Holds SIG of OS as four byte HEX string
Public Sig_Value_Dec 'Holds sig as a decimal number
'Change this address to match the SDM-SIO1A SDM Adress
Const SDM_Address=0
Dim SRC As String *1
Const cmd = 5 'constant cmd = 0..7
Const bytes_out = 1 'constant number of bytes out
Const bytes_val = 1 'constant bytes per value (1,2,4)
Const big_endian = 1 'constant 1 (big endian) or 0 (little endian)
Const Delay_usec = -0 'constant delay between outgoing bytes (negative means delay 'also for incoming bytes
Const Ver_values_in = 20'constant number of values to receive
Const Sig_values_in = 4'constant number of values to recieve
SequentialMode
BeginProg
SDMSPeed (30) 'Fix the speed
Ver_Value = ""
Sig_Value = ""
Scan (1,Sec,0,0)
'Use the generic SDM instruction to get extra info from the SDM-SIO1A
'Ask for the operating system version
Src = CHR(1)
SDMGeneric (Ver_Value,SDM_Address,cmd,bytes_out,Src,Ver_values_in,bytes_val,big_endian,delay_usec)
'Read signature
Src = CHR(2)
SDMGeneric (Sig_Value,SDM_Address,cmd,bytes_out,Src,Sig_values_in,bytes_val,big_endian,delay_usec)
Sig_Value_Dec = HexToDec (Sig_Value)'Convert sig to decimal too.
NextScan
EndProg
Parameters
Dest
A variable that will hold any incoming bytes from the SDM device.
Type: Variable or variable array
SDMAddress (Address of Device)
Defines the address of the device with which to communicate. Valid SDM Synchronous Device for Measurement. A processor-based peripheral device or sensor that communicates with the datalogger via hardwire over a short distance using a protocol proprietary to Campbell Scientific. addresses are 0 through 14. Address 15 is reserved for the SDMTrigger instruction.
Some SDM instructions support repetitions. If a Reps parameter is present and it is greater than 1, the data logger will increment the SDM address used in the instruction for each subsequent device with which it communicates.
CmdByte
A setup byte that will be sent to the SDM device.
Type: Variable or constant
NumValsOut
The number of values that are to be sent to the SDM device.
Type: Variable or constant
Source
A variable that holds the values to be sent to the SDM device.
Type: Variable
NumValsIn
The number of values that are expected to be received back from the SDM device.
Type: Variable or constant
BytesPerValue
The number of bytes for each value sent to or received from the SDM device. Typically, this is 1, 2, or 4, for 1 byte, 2 byte, or 4 byte values.
Type: Variable or constant
BigEndian
Indicates the order of bytes to be sent or received. Enter 0 for little endian (least significant byte first), or 1 for big endian (most significant byte first).
Type: Constant
DelayByte
The delay, in microseconds, that should be used between sending bytes. If a negative value is entered, this is the delay to be expected between receiving bytes from the SDM device.
Type: Constant