Allen-Bradley FLEX I/O 1794-IP4, User Manual, Page: 48 / 70

5–4 How Communication Takes Place and I/O Image Table Mapping with the DeviceNet Adapter
Publication 1794-6.5.16 – September 1998
Block Transfer Read Word Assignments for the Pulse Counter
Module (1794-IP4)
(Octal Bit
⇒
) 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00
Dec. Bit
⇒
15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00
Word
⇓
Read
1 Counter 00 – 16–bit period measurement or low word of 32-bit period measurement for channel 0
2 Counter 01 – pulse counter or high word of 32-bit period measurement for channel 0
3 Counter 10 – 16–bit period measurement or low word of 32-bit period measurement for channel 1
4 Counter 11 – pulse counter or high word of 32-bit period measurement for channel 1
5 Counter 20 – 16–bit period measurement or low word of 32-bit period measurement for channel 2
6 Counter 21 – pulse counter or high word of 32-bit period measurement for channel 2
7 Counter 30 – 16–bit period measurement or low word of 32-bit period measurement for channel 3
8 Counter 31 – pulse counter or high word of 32-bit period measurement for channel 3
9
Readback of Control Word 2
9
Reserved M3 M2 M1 M0
10 Revision read – software version code
Where: M = positive edge measurement ready for the respective channel.
Block Transfer Write Word Assignments for the Pulse Counter
Module
(Octal Bit)
⇒
17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00
Dec. Bit
⇒
15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00
Word
⇓
Write
1 Control Word 0 – selects the measure function
2 Control Word 1 – sets the clock frequency and period multiple
3 Control Word 2 – sets the start of a new measurement
4–5 Reserved
Bit/Word Definitions
for the Pulse Counter Module
Word Bit Definition
Read
Word 1
Bits 00–15
(00–17)
Store Counter 00 – 16–bit period measurement or low word of 32-bit period measurement for channel 0.
Read
Word 2
Bits 00–15
(00–17)
Counter 01 – pulse counter or high word of 32-bit period measurement for channel 0
Read
Word 3
Bits 00–15
(00–17)
Counter 10 – 16–bit period measurement or low word of 32-bit period measurement for channel 1.
Read
Word 4
Bits 00–15
(00–17)
Counter 11 – pulse counter or high word of 32-bit period measurement for channel 1
Read
Word 5
Bits 00–15
(00–17)
Counter 20 – 16–bit period measurement or low word of 32-bit period measurement for channel 2.