Rockwell Automation 1756-L55M12, Selection Manual, Page: 14 / 88

12
1756-SG001G-EN-P — March 2004
1756 Specialty I/O
Modules
1756-CFM configurable flow meter
The 1756-CFM module provides totalizer mode for metering applications, or high-
speed frequency measurements for speed or rate control applications, on two
channels connected to flowmeters. Both Fill and Prover functions are supported
within resettable or nonresettable totalizer mode. A 12-segment K-factor correction
table makes it easy to scale any turbine flowmeter and AGA 7 compensation is
available.
The module supports two configurable outputs that can be connected to one or both
channels and can be triggered on:
y
flow or frequency
y
acceleration
y
full flow state
y
trickle flow state
y
prover run state
y
prover range state
The module interfaces devices such as:
y
magnetic pickup flow meters
y
4-40V dc pulses (TTL compatible)
y
proximity probes
Cat. No. Mode of Operation
Number of Inputs per
Channel Voltage, Flowmeter
Input Removable Terminal
Block Housing Backplane Current
(mA) at 5V Backplane Current
(mA) at 24V Power Dissipation,
Max.
1756-CFM
Totalizer fill and prover
High-Resolution 100 kHz
max.
Frequency 0.0005 Hz
resolution 2 – Flowmeter (F) Input
– used for all modes
2 – Gate Input – used in
Totalizer Mode for
Prover/Store Count
± 30V - Selectable input
thresholds of 50 mV,
1.3V & 4V:
± 30V peak
unterminated open
circuit voltage –
Magnetic Pickup
TTL Compatible – Input
Voltage greater than 1.3V
dc is Logic 1 and - 0.7V
dc…1.3V dc is Logic 0
12…24V dc powered
preamp output - 4V dc
threshold
1756-TBNH
1756-TBSH
300 mA 6 mA 6 W @ 60°C