Rockwell Automation 1794-IP4/B INSTL INSTR 24V dc FLEX I/O 4 CHANNEL User Manual
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Publication 1794-IN064D-EN-P - March 2005
Description of Control Word 0
Filter Function Description
Use the filter in either 16-bit or 32-bit mode. Enable filter to use a triangular
shape waveform of frequencies as low as 1Hz. If the filter is not enabled, the
module will only function properly with input waveform of square shape.
Description of Control Word 1
Description of Control Word 2
Description of Control Word 2 Readback
Bit
Description
Bit 0
Pulse Counting and period time measurement selection for Channel 0
0 = pulse counting and period time measurement selected - 16-bit
1 = period time measurement selected - 32-bit
Bit 01
Pulse Counting and period time measurement selection for Channel 1
0 = pulse counting and period time measurement selected - 16-bit
1 = period time measurement selected- 32-bit
Bit 02
Pulse Counting and period time measurement selection for Channel 2
0 = pulse counting and period time measurement selected - 16-bit
1 = period time measurement selected- 32-bit
Bit 03
Pulse Counting and period time measurement selection for Channel 3
0 = pulse counting and period time measurement selected - 16-bit
1 = period time measurement selected- 32-bit
Bit 04
Channel 0 - 0 = filter disabled; 1 = filter enabled
1
Bit 05
Channel 1 - 0 = filter disabled; 1 = filter enabled
1
Bit 06
Channel 2 - 0 = filter disabled; 1 = filter enabled
1
Bit 07
Channel 3 - 0 = filter disabled; 1 = filter enabled
1
Bits
08-09
09
08
Filter sample clock frequency and period (common to all
channels)
0
0
625kHz
1.6
µs
0
1
312.5kHz
3.2
µs
1
0
104.17kHz
9.6
µs
1
1
7.8125kHz
128
µs
Bits
10-15
Reserved
1
Use filter when the input waveform has slow rise/fall time or has high frequency noise on the
input waveform.
ATTENTION
Do not enable the filter with frequencies greater than
90kHz. A loss of counts may result.
Bit
Description
00
Clock Frequency for period time measurement - Channel 0
0 = period time measurement with 10MHz internal clock selected
1 = period time measurement with 1MHz internal clock selected
01-03
03
02
01
Number of periods for measurement - Channel 0
0
0
0
1 period
0
0
1
2 period
0
1
0
4 period
0
1
1
8 period
1
0
0
16 period
1
0
1
32 period
1
1
0
64 period
1
1
1
128 period
04
Clock frequency for period time measurement - Channel 1 - refer to bit 00
05-07
Selection of number of periods for measurement - Channel 1 - see bits 01-03
08
Clock frequency for period time measurement - Channel 2 - refer to bit 00
09-11
Selection of number of periods for measurement - Channel 2 - see bits 01-03
12
Clock frequency for period time measurement - Channel 3 - refer to bit 00
13-15
Selection of number of periods for measurement - Channel 3 - see bits 01-03
Bit
Description
00
Start new measurement - Channel 0 - when set, start new
measurement on positive edge
01
Start new measurement - Channel 1 - when set, start new
measurement on positive edge
02
Start new measurement - Channel 2 - when set, start new
measurement on positive edge
03
Start new measurement - Channel 3 - when set, start new
measurement on positive edge
04
Reset Counter, Channel 0 - a positive edge on this bit resets counter 01
05
Reset Counter, Channel 01- a positive edge on this bit resets counter 11
06
Reset Counter, Channel 2 - a positive edge on this bit resets counter 21
07
Reset Counter, Channel 3 - a positive edge on this bit resets counter 31
08-15
Reserved for factory use
Bit
Description
00
Positive edge - Channel 0 - measurement ready
01
Positive edge - Channel 1 - measurement ready
02
Positive edge - Channel 2 - measurement ready
03
Positive edge - Channel 3 - measurement ready
04
Reset Counter, Channel 0 - a positive edge on this bit indicates counter 01
reset done
05
Reset Counter, Channel 1 - a positive edge on this bit indicates counter 11
reset done
06
Reset Counter, Channel 2 - a positive edge on this bit indicates counter 21
reset done
07
Reset Counter, Channel 3 - a positive edge on this bit indicates counter 31
reset done
08-15
Reserved for factory use