Reads the current state of one or more digital inputs.
- Parameters
-
| [in] | handle | Valid handle returned by SM_Open(). |
| [in] | start | Starting input (zero-indexed). |
| [in] | number | Quantity of inputs to read. |
| [out] | values | Discrete input values. |
- Return values
-
| >=0 | Number of bytes successfully returned in result array. |
| -1 | Invalid SeaMAX handle. |
| -2 | Modbus: Connection is not established. Check the provided Connection object state. |
| -3 | Modbus: Read error waiting for response. Unknown Modbus exception. |
| -4 | Modbus: Illegal Modbus Function (Modbus Exception 0x01). |
| -5 | Modbus: Illegal Data Address (Modbus Exception 0x02). |
| -6 | Modbus: Illegal Data Value (Modbus Exception 0x03). |
| -7 | Modbus CRC was invalid. Possible communications problem. |
| -20 | SeaDAC Lite: Invalid model number. |
| -21 | SeaDAC Lite: Invalid addressing. |
| -22 | SeaDAC Lite: Error reading the device. |
Reads the state of one or more digital inputs. The digital input values in the values array (after a successful read) are packed as one input per bit. The LSB of the first byte (values[0]) contains the first addressed input. The next inputs follow toward the high order end of this byte, and then from low order to high order in subsequent bytes.
For instance, a read of 18 inputs would result in a three byte values array:
values[0] = Input 7 to Input 0 (MSB to LSB)
values[1] = Input 15 to Input 8
values[2] = 6 Padding bits followed by Input 17 to Input 16
- Warning
- The parameter
values must have enough allocated space, before calling this method, to hold 1 bit for every input requested.
Referenced by SM_ReadDiscreteInputs().
