Allen-Bradley FLEX I/O 1794-ID2, Руководство пользователя, Страница: 57 / 84

5–7 How Communication Takes Place and I/O Image Table Mapping with the DeviceNet Adapter
Publication 1794-6.5.15 – December 1998
Definition Bit Word
Write
Wor 2
Channel 1 Control Word – Control word for setting the function of counter 1.
Word 2
Bits 00–02 Bit 02 01 00 Mode Selection bits
0 0 0 Counting on positive (rising) edge of input signal A. (Up/dwn counting determined by B.)
0 0 1 Quadrature encoder X1
0 1 0 Quadrature encoder X2
0 1 1 Quadrature encoder X4
1 0 0 Counting up on the positive edge of input signal A, and down on positive edge of input
signal B.
1 0 1 No count function.
1 1 0 No count function.
1 1 1 No count function.
Bit 03 Preset bit – A positive edge on this bit moves the value in Preset X to Counter X, independent of Preset Enable.
Bit 04 Preset Enable bit – When this bit is set (1), a positive edge on Z preloads Counter X = Preset X, independent of
Cal Enable.
Bit 05 Count Enable bit – When this is set (1), the incremental encoder is counting.
Bits 06–08
06–10
Calibration Control bits – bits 06, 07 and 08
(06–10)
06 Enable bit – When this bit is set (1), the counter can be calibrated.
07 Direction bit – When this bit set (1), calibration is performed in a negative direction; when reset (0),
calibration is performed in a positive direction.
08 Reset bit – Calibration is acknowledged and a new calibration is enabled on a positive edge on this bit.
Bits 09–10
11–12
10 09 Gate Control bits
(11–12)
0 0 No gate function on input G
0 1 Counting only if G is high (active)
1 0 Counting only if G is low (inactive)
1 1 Calibration if G is high (active) and ???
Bits 11–12
13–14
12 11 Latch Control bits
(13–14)
0 0 Save the counter value on the positive edge of Z (if Stored X = 0)
0 1 Save the counter value on the positive edge of G (if Stored X = 0)
1 0 Save the counter value on the negative edge of G (if Stored X = 0)
1 1 Save the counter value on the positive edge and negative edge of G (if Stored X = 0)
Bit 13 (15) Rollover bit – When set (1), the counter counts up to the preset and then restarts at 0. If this bit is reset (0) (not
rollover), the rollover preset value = FFFF (hex = 65535 (decimal).
Bit 14 (16) Store Reset bit – A positive edge on this bit resets Stored X in Signals.
Bit 15 (17) Store Reset bit – A positive edge on this bit resets Preset Reached in Signals.
Write
Word 3
Bits 00–15
(00–17)
Preset 0 – Value to load or compare with counter 0
Write
Word 4
Bits 00–15
(00–17)
Preset 1 – Value to load or compare with counter 1
Write
Words
5–7
Bits 00–15
(00–17)
Not used – set to 0.
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