Overview, Features and specifications, Installation checklist – Obvius A8911-23 User Manual
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Overview
The A8911-23 is designed for pulse counting applications where large number of pulse output devices need to be connected
to a Modbus network. The A8911-23 will count contact closures on 23 separate inputs and store the totalized pulse count
internally using non-volatile memory. The pulse count totals are then read using the RS485/Modbus protocol. Applications
include reading gas/water/electric meters in common building areas for energy information and reporting purposes.
Features and Specifications
Processor
Arm7, field upgradeable firmware.
LED
23 input status LEDs (red), 2 Modbus TX/RX (yellow), 1 power/alive status. (green)
Protocols
Modbus/RTU
Power Supply
9VDC to 30VDC, 200mA, Required (not included)
Serial Port
1
RS-485 two wire, 19200 or 9600 baud. N81
Pulse Inputs
1
23 independent pulse count inputs.
Intended for use with isolated dry contact outputs.
Pulse rate/width user selectable to 10hz, 50hz or 100hz.
Pulse rate option: 10hz, minimum pulse width 50ms
Pulse rate option: 50hz, minimum pulse width 10ms
Pulse rate option: 100hz, minimum pulse width 5ms
Contact closure threshold 100
Ω
to 2.5k
Ω
user selectable
Pulse count values are stored in non-volatile memory.
Isolation
2
:
Pulse inputs, power input and RS485 are non-isolated.
Environmental
North America: Indoor, temperature 0º - 50ºc, 0 - 95% humidity, non-condensing.
Europe: Indoor, temperature 5º - 40ºc, 0 - 90% humidity, non-condensing.
EMC
FCC CFR 47 Part 15, Class A
Size
4.13” x 3.39” x 1.18” (105mm x 86mm x 30mm)
Mass
3.7 oz (105 g)
1
inputs are intended for low voltage class 2 outputs.
2
if the product is used in a manner not specified by the manufacture, the protection provided by the equipment may be
impaired.
Installation Checklist
The following components are required for a complete A8911-23 I/O module installation:
●
A8911-23 I/O module
●
Modbus/RTU master device such as an AcquiSuite™ A8812 server
●
Pulse output meter
●
Power supply: 24VDC typical. (9VDC to 30VDC ok)
●
Wire. Typically 18 to 24 gauge
3
for pulse meter connection.
●
2 wire, twisted pair with shield for Modbus/RS485 connection. (Belden 1120A or equivalent)
3
●
Optional: Termination resistor (120 ohm) for long RS485 runs over 200ft.
3
Wire connected to pulse meters inside high voltage panels should have an insulation rating in excess of the service voltage.
Consult a licensed electrician and local building codes for further requirements that may apply.
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A8911-23