BusWorks® Model 989EN U
ser’s Manual Modbus TCP/IP Digital I/O & Counters
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Acromag, Inc. Tel:248-295-0880 Fax:248-624-9234 Email:
9
INP
+
RTN
EXC
V+
I/O
(INT PULL-UP)
5.5V MIN
EXT
EXC
EXTERNAL DRIVER MUST BE PULLED UP ABOVE 4V INPUT THRESHOLD.
EXTERNAL PULLUP IS ADDED HERE TO INCREASE CURRENT.
IF NOT TRI-STATED, INTERNAL WETTING CURRENT IS SET TO 2mA.
INPUTS MAY OPTIONALLY BE TRI-STATED TO TURN OFF WETTING CURRENT.
TANDEM OUTPUT MOSFET IS OFF.
EXCITATION IS REQUIRED (8-28V).
SOLID-STATE RELAY MONITOR
TIP:
You can increase wetting currents by paralleling I/O channels, or by
adding an external pull-up resistor from I/O to an external excitation source.
TIP:
Unused tri-stated inputs can be pulled to the ON state if you also
enable the tandem output open-load detection (this adds 50uA pull-downs in
the output OFF state).
Note that wetting currents are slightly lower than 2mA/16mA for excitation
voltages below 8V. They will also vary slightly with the number of channels
turned ON. Use external excitation equal to or above 8V to properly regulate
this current to 2mA/16mA.
V
ON
+
_
RTN
EXC
CNT
Generator
Frequency
8-28V
OPEN-DRAIN OUT PUT S SHARE RET URN.
EXT
EXC
SHIELDED
CABLE
OFF
EXCIT AT ION IS REQUIRED. EXT ERNAL EXCIT AT ION IS 8V MIN T O 31V MAX.
PIN CAN BE USED AS COUNT ER OR DIGIT AL I/O LINE
EVENT COUNT ER IS RAT ED FOR FREQUENCIES 0-150HZ
FREQUENCY INPUT CONNECTION
CONNECTIONS
Digital Inputs
Solid-State Relay (SSR)
Monitoring
Tri-stating the inputs will turn
off the wetting current pull-ups
and the input will then act like
a high-impedance comparator
with a 4V logic threshold. If tri-
stated inputs are left
unconnected, the I/O channels
float and will need to be tied
OFF to properly register the
OFF state (you could
optionally use output open-
load detection to pull-down
unused tri-stated inputs
—see
TIP below).
Frequency Input Connection
(989EN-4016 Only)
Input Event Counters are rated
from 0 to 150 Hz with signal
voltages from 0 to 28 VDC (4V
Threshold). Your excitation
voltage determines your input
voltage signal range
maximum. These 32-bit
counters are additionally
equipped with a programmable
debounce, up/down counting,
selectable edge, and count
auto-restore after a power
reset.
