Section 5. Programming the Datalogger
5-17
^J^M
– this is a way of entering control characters for carriage return/linefeed
into a string
The following program example works as follows:
1.
The first P113 sets up a simple filter to search for floating point numbers.
2.
The first parameter of this command is used to transmit a string which will
prompt the sensor into taking measurements and then transmitting the numbers
to the SDM-SIO4.
3.
A delay is required by the set up formatter command and is calculated as
follows:
delay=chars*0.26*ports.
This works out as the following: 11*0.26*1 = 2.86ms. Also you will have to
wait long enough for the sensor to respond which must include the time to
receive and transmit the data. This example is using a 9600 baud rate, and so
11 characters could take 12ms for the sensor command and another 20
characters (21ms) for output data from the sensor. The total time before the
datalogger can get the data would therefore be 2.86+12+21 = 35.86ms. This
time does not allow for any delay that the sensor may have in executing and
taking any measurements. This example gives the sensor 4.24ms for
measurements by giving P22 a 40ms delay.
4.
By doing the above, the datalogger can get the two floating point values
returned from the sensor into locations 1 and 2.
*Table 1 Program
01: 2 Execution Interval (seconds)
;set up the filter and then send string 101.
1: SDM-SIO4 (P113)
1: 1 Reps
2: 0 Address
3: 1 Send/Receive Port 1
4: 2304 Command
5: 8101 1st Parameters
6: 1999 2nd Parameters
7: 0 Values per Rep
8: 0 Loc [ ]
9: 1.0 Mult
10: 0.0 Offset
;wait long enough for sensor to send data.
2: Excitation with Delay (P22)
1: 1 Ex Channel
2: 0 Delay W/Ex (units = 0.01 sec)
3: 4 Delay After Ex (units = 0.01 sec)
4: 0 mV Excitation
