Campbell SDM-SIO2R, Product Manual

Page: 46 / 57

CRBasic Example 2: Detecting the state of the input line
'CR1000 example program showing how to detect the state of the input line on an
'SDM-SIO2R using the SDMGeneric instruction
Public sio1response As Long, Inputstate As Boolean
Const addr = 0 'constant sdm address CHANGE with SDM-SIO2R address
Const cmd = 1 'constant, command 1 returns the input state in bit 16
Const bytes_out = 0 'constant number of bytes out - none sent
Const bytes_val = 2 'two bytes returned
Const big_endian = 1 '1=(big endian)
Const delay_usec = -0 'delay between outgoing bytes (negative means delay also
'for incoming bytes)
Const Values_in = 1
'Main Program
BeginProg
Scan (1,Sec,0,0) 'Or whatever scan rate is being used
'Use the SDMGeneric instruction to send command 0x01 which returns the input
'line state as bit 16
SDMGeneric (sio1response,addr,cmd,bytes_out, "" ,Values_in,bytes_val, _
big_endian,delay_usec)
'bit 16 set for input line high or low so check the value and set a Boolean
'var TRUE or FALSE accordingly
Inputstate = sio1response AND &H8000
NextScan
EndProg
The input line can accept 0 and 5V logic inputs OR –12 and +12V RS-232 level inputs. The
following table shows a breakdown of the different input voltages allowed and the state of the
input line flag.
Voltage on the input line State of bit 16
+12V 1
–12V 0
5V 1
0V 0
A.2 The output pin (RTS)
To set the output pin (RTS) you must use the
SerialOutBlock()
instruction.
The spare I/O lines are RS-232 lines, NOT logic lines. This means that the output line voltage is
–12V and +12V (approximately), not 0 and 5V.
SDM-SIO2R Serial Input/Output Module with Switched Sensor Power 43