USB-I/O Interface Adapter GPIO-24. Programmer's Reference Manual.
11.6. GPIO_GET_PLS_CNT_LIMIT (0x29)
The GPIO_GET_PLS_CNT_VAL command retrieves current number of detected pulses or elapsed time for specified pulse counter.
GPIO_GET_PLS_CNT_VAL Command
| Byte 0 | GPIO_GET_PLS_CNT_VAL | Command ID (must be 0x1F) |
| Byte 1 | ECHO | Echo to associate the command with the response |
| Byte 2 | PLS_CNT_NUMBER | ID number of the counter, which readings will be retrieved. |
| Byte 3 | VALUE_TYPE | Type of the counter value (elapsed time or current number of detected pulses) |
| Bytes 4..7 | Reserved | Reserved |
Command is an 8-byte array of the following format:
- Byte 0: GPIO_GET_PLS_CNT_VAL (0x1F)
This byte contains command ID (command type). It must be set to 0x1F.
- Byte 1: ECHO
This byte can be used to associate a response received from GPIO-24 adapter with a specific command. Response will contain exactly the same value in its echo byte.
- Byte 2: PLS_CNT_NUMBER
The ID number of the pulse counter:
0 – pulse counter on A.3 pin;
1 – pulse counter on A.4 pin.
- Byte 3: VALUE_TYPE
The type of value to be returned in the response:
GPIO_PLS_CNT_VAL_PULSES (0) – The response will contain the number of detected pulses.
GPIO_PLS_CNT_VAL_TIME (1) – The response will contain the elapsed time in units of 10 ms.
- Bytes 4..7: Reserved
These bytes are reserved for future usage and must be set to 0.
For convenience GPIO_GET_PLS_CNT_VAL_CMD structure is declared in reports.h file.
GPIO-24 adapter sends GPIO_GET_PLS_CNT_VAL response after command execution. Current pulse counter readings are specified inside the response.
GPIO_GET_PLS_CNT_VAL Response
| Byte 0 | GPIO_GET_PLS_CNT_VAL | Command ID (must be 0x1F) |
| Byte 1 | ECHO | Echo to associate the command with the response |
| Byte 2 | ST | Command execution status |
| Byte 3 | PLS_CNT_NUMBER | ID number of the counter, which readings are retrieved. |
| Byte 4 | VALUE_TYPE | Type of the counter value (elapsed time or current number of detected pulses) |
| Byte 5 | VALUE[2] | Current number of detected pulses or elapsed time |
| Byte 6 | VALUE[1] | |
| Byte 7 | VALUE[0] |
Response is an 8-byte array of the following format:
- Byte 0: GPIO_GET_PLS_CNT_VAL (0x1F)
Response ID (response type). This byte will contain 0x1F.
- Byte 1: ECHO
Echo byte copied from the corresponding command. It can be used to associate the response with the specific command.
- Byte 2: ST
Status of the command execution:
GPIO_ST_SUCCESS (0x00) – Pulse counter readings has succesfully been retrieved;
GPIO_ST_INVALID_PLS_CNT_NUMBER (0x0A) – Invalid ID of the pulse counter has been specified (only 0 and 1 values are valid);
GPIO_ST_INVALID_PARAMETER (0x0B) – Unsupported pulse counter value type has been specified.
- Byte 3: PLS_CNT_NUMBER
The ID number of the pulse counter:
0 – pulse counter on A.3 pin;
1 – pulse counter on A.4 pin.
- Byte 4: VALUE_TYPE
The type of value specified in Bytes 5..7: VALUE:
GPIO_PLS_CNT_VAL_PULSES (0) – Bytes 5..7: VALUE contain the number of detected pulses.
GPIO_PLS_CNT_VAL_TIME (1) – Bytes 5..7: VALUE contain the elapsed time in units of 10 ms.
- Bytes 5..7: VALUE
If Byte 4: VALUE_TYPE equals to GPIO_PLS_CNT_VAL_PULSES (0), Bytes 5..7: VALUE contain the time period in units of 10 ms, that have passed since last reset of the pulse counter.
If Byte 4: VALUE_TYPE equals to GPIO_PLS_CNT_VAL_TIME (1), Bytes 5..7: VALUE contain current number of pulses counted since last reset of the pulse counter.
Byte 5: VALUE[2] – least significant byte (low byte) of a pulse counter readings.
Byte 6: VALUE[1] – middle byte of threshold a pulse counter readings.
Byte 7: VALUE[0] – most significant byte (high byte) of a pulse counter readings.
For convenience GPIO_GET_PLS_CNT_VAL_RSP structure is declared in reports.h file.
