National Instruments SCXI-1120 - Manual (Page 73)

Programming Chapter 5
SCXI-1120 User Manual 5-2 © National Instruments Corporation
Table 5-1. SCXI-1120 Rear Signal Connector Pin Equivalences
SCXIbus Line SCXI-1120 Rear
Signal Connector
MIO-16 Board Lab-NB/Lab-PC/
Lab-PC+/Lab-LC
PC-LPM-16
MOSI SERDATIN ADIO0 PB4 DOUT4
D*/A DAQD*/A ADIO1 PB5 DOUT5
INTR* SLOT0SEL* ADIO2 PB6 DOUT6
SPICLK SERCLK EXTSTROBE* PB7 DOUT7
MISO SERDATOUT BDIO0 PC1 DIN6
Register Selection and Write Procedure
1. Select the slot of the module to be written to (or Slot 13 or 14). Initial conditions:
SERDATIN = X.
DAQD*/A = X.
SLOT0SEL* = 1.
SERCLK = 1.
2. Clear SLOT0SEL* to 0. This will deassert all SS* lines to all modules in all chassis.
3. For each bit, starting with the MSB (bit 15):
a. SERDATIN = bit to be sent. These bits are the data that is being written to the
Slot-Select Register.
b. Clear SERCLK to 0.
c. Set SERCLK to 1. This rising edge clocks the data. (If you are using an MIO-16 board,
writing to the EXTSTROBE* register will pulse EXTSTROBE* low and then high,
accomplishing steps 3b and 3c.)
4. Set SLOT0SEL* to 1. This will assert the SS* line of the module whose slot number was
written to Slot 0. If you are using multiple chassis, only the appropriate slot in the chassis
whose address corresponds to the written chassis number will be selected automatically.
When no communications are taking place between the data acquisition board and any
modules, write zero to the Slot-Select Register to ensure that no accidental writes occur.
5. If you are writing to a Configuration Register, clear DAQD*/A to 0 (this indicates data will
be written to Configuration Register). If you are writing to the HSCR or FIFO Register,
leave DAQD*/A high.
6. For each bit to be written to the Configuration Register:
a. Establish desired SERDATIN level corresponding to this bit.
b. Clear SERCLK to 0.
c. Set SERCLK to 1 (clock the data). (If you are using an MIO-16 board, writing to the
EXTSTROBE* register will pulse EXTSTROBE* low and then high, accomplishing
steps 6b and 6c.)