Campbell Scientific SDM-IO16 16-Channel Input/Output Expansion Module - Manual (Page 23)

SDM-IO16 16 Channel Input/Output Expansion Module
Set the interrupt mask (97..98): these commands set a binary mask across the
ports to define whether a change of state on the port (which must also be
configured as an input) will generate an interrupt signal to the datalogger.
When the appropriate mask bit representing the port is set to 1 an interrupt will
be generated whenever the port changes state. The interrupt is generated by
pulsing the I/O line on the SDM-IO16 until the datalogger responds by reading
the port states of the SDM-IO16 in question using the SDM-IO16 command.
The I/O line would normally be connected to a control port on the datalogger
that activates an interrupt subroutine. When the I/O line is not pulsing, it
switches to a high impedance state, which means that several similar I/O lines
can be connected in parallel to the same control port on the datalogger.
Read module status (99): reads back the module operating system signature
(which is calculated once at power-up), a number which identifies the
operating system version plus two counters. These are a watchdog error
counter which is incremented if the module crashes because of a software or
hardware failure that required the SDM-IO16 to be reset and a communication
error counter which represents the number of times SDM communication
between the datalogger and SDM-IO16 failed. Both counters have a maximum
limit of 255 counts and are reset to zero when this command code is used to
read them. This command is only normally used when trying to diagnose
problems with the datalogging system.
TABLE 3. Summary of the Common Command Codes (in italics) relative to port number and function.
Port Number
Action
Port
Blocksize
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
1 Port 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
4 Ports 17 18 19 20
8 Ports 21 22
Read
Counts
16 Ports 23
1 Port 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39
4 Ports 40 41 42 43
8 Ports 44 45
Read
Frequency
16 Ports 46
1 Port 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62
4 Ports 63 64 65 66
8 Ports 67 68
Read
Duty Cycle
16 Ports 69
Set Debounce 1 Port 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85
4 Ports 89 88 87 86 Set-up
ports 16 Ports 90
Read State 16 ports 91 or 92
Set state 16 ports 93 or 94
Set Direct. 16 ports 95 or 96
Set Int Mask 16 ports 97 or 98
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