1
1 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.
1.1 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)
The unit is to be sourced by a NEC Class 2 power supply, or Listed ITE power
supply marked LPS and rated from 9 to 30Vdc, 200 mA minimum but not to
exceed 8A
Serial Port1RS-485 two wire, 19200 or 9600 baud. N81
Pulse Inputs123 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 to 2.5k user selectable
Pulse count values are stored in non-volatile memory.
Isolation2: Pulse inputs, power input and RS485 are non-isolated.
Environmental Pollution Degree 2, Altitude up to 2000M.
For indoor and outdoor use when used in an appropriate enclosure.
The A8911-23 must be mounted inside a NEMA rated electrical enclosure for safety
and isolation requirements.
North America: Indoor, temperature -30º - +70ºc, 0 - 95% humidity,
non-condensing3
Safety UL61010 Recognized3
File: E320540 (Model A8911-23)
EMC FCC CFR 47 Part 15, Class A
EN 61000, EN 61326
Size 4.13” x 3.39” x 1.18” (105mm x 86mm x 30mm)
Mass 3.7 oz (105 g)
1inputs are intended for low voltage NEC Class 2 or equivalent outputs.
2if the product is used in a manner not specified by the manufacture, the protection provided by the
equipment may be impaired.
3Devices manufactured before Nov 1, 2011 are rated to 0 ~ 50c, and are not UL recognized.
