Obvius A8911-23 User Manual

A8911-23 Modbus Pulse Input Module

Obvius, LLC

Installation and Operation Manual

Date Jun 21, 2010

Page 1 A8911-23

Copyright Information

Copyright © 2006 - 2010 by Obvius

Obvius and AcquiSuite are trademarks of Obvius Holdings LLc

Other brand and product names are trademarks or registered trademarks of their respective holders.

U.S. Government Restricted Rights: Use, duplication or disclosure by the Government is subject to restrictions set fourth in subparagraph (a) through
(d) of the Commercial Computer Restricted Rights clause at FAR 52.227-19 when applicable, or subparagraph (c) (1) (ii) of the Rights in Technical Data
and Computer Software clause at DFARS 252.227-7013, and in similar clauses in the NASA FAR Supplement.

Limited Warranty

OBVIUS IS PROVIDING THIS WARRANTY IN LIEU OF ALL OTHER EXPRESS OR IMPLIED WARRANTIES, INCLUDING ANY WARRANTY
OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. THIS WARRANTY IS BUYER'S EXCLUSIVE REMEDY FOR ALL
CLAIMS AGAINST OBVIUS. OBVIUS SHALL NOT BE LIABLE FOR ANY CONSEQUENTIAL OR INCIDENTAL DAMAGES. OBVIUS'S TOTAL
LIABILITY FOR ALL CLAIMS SHALL BE LIMITED TO THE PRICE PAID FOR ITS PRODUCT.

Obvius promises buyer that any standard product manufactured by Obvius shall be free from all material defects in design, material, or manufacturing for
a period of 2 years from the manufacture date; provided, however, that the warranty shall not extend to ordinary wear and tear or to normally replaceable
components (e.g., batteries). During the warranty period, Obvius may repair or replace (in its sole discretion) any product suffering from a warranty defect
and returned freight prepaid by buyer, with no charge to buyer for any warranty repair or replacement. The warranty shall remain in full force and effect
for such 2 year period, provided that the product: (1) was installed, operated, and maintained properly; (2) has not been abused or misused; (3) has not
been repaired, altered, or modified outside of Obvius's authorized facilities; (4) has not been sold subject to other warranty terms specified at the time of
sale; and (5) is still owned by the original purchaser. This warranty provides specific legal rights that may be varied by state law. Obvius's products are not
designed for life or safety applications.

Product Application Limitation

Obvius products are not intended for use in critical applications such as nuclear facilities, human implantable devices or life support. Obvius is not liable,
in whole or in part, for any claims or damages arising from such uses.

Obvius strongly believes in continuous improvement, therefore we must reserve the right to change specifications and product offerings without notice.
Where possible, we will substitute products with equivalent functionality when necessary.

NOTICE

● This product is not intended for life safety applications.

● Do not install this product in hazardous or classified locations.

● The installer is responsible for conformance to all applicable codes.

FCC Part 15 Information

Note: This equipment has been tested by the manufacturer and found to comply with the limits of a class A digital device, pursuant to part
15 of the FCC rules. These limits are designed to provide reasonable protection against interference when the equipment is operated in a
commercial environment. This equipment generates, uses, and can radiate radio frequency energy and, if not installed and used in
accordance with the instruction manual, may cause harmful interference to radio communications. Operation of this equipment in a
residential area is likely to cause harmful interference in which case the user will be required to correct the interference at his own expense.
Modifications of this product without the express authorization of Obvius nullify this statement.

Obvius
3300 NW 211th Terrace
Hillsboro, OR 97007
ph: 503-601-2099
www.obvius.com

Page 2 A8911-23

Table of Contents

Markings and Symbols:...............................................................................................................................................................3

Overview......................................................................................................................................................................................4

Features and Specifications.........................................................................................................................................................4

Installation Checklist...................................................................................................................................................................4

Electrical Connections.................................................................................................................................................................5

Hardware Installation...................................................................................................................................................................5

Configuration...............................................................................................................................................................................6

Operation.....................................................................................................................................................................................6

Troubleshooting...........................................................................................................................................................................7

Register Listing......................................................................................................................................................................7

Register Functions..................................................................................................................................................................9

Mechanical Drawings................................................................................................................................................................10

Markings and Symbols:

WARNING: A potential risk exists if the operating instructions are not followed

General Warning Symbol: This symbol indicates the need to consult the operating instructions provided with the
product.

This symbol indicates the presence of electric shock hazards.

This symbol indicates: Do not apply to or remove from hazardous live conductors.

Direct Current symbol.

Page 3 A8911-23

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
Pulse Inputs

Isolation2: Pulse inputs, power input and RS485 are non-isolated.
Environmental North America: Indoor, temperature 0º - 50ºc, 0 - 95% 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

1

RS-485 two wire, 19200 or 9600 baud. N81
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 100Ω to 2.5kΩ user selectable

Pulse count values are stored in non-volatile memory.

Europe: Indoor, temperature 5º - 40ºc, 0 - 90% humidity, non-condensing.

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

● 2 wire, twisted pair with shield for Modbus/RS485 connection. (Belden 1120A or equivalent)

● 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.

3

for pulse meter connection.

3

Page 4 A8911-23

Electrical Connections

Hardware Installation

1) Mount the A8911-23 on a DIN-Rail or appropriate mounting enclosure.

2) Attach the power supply to the input terminals on the A8911-23 module.

3) Turn on the power supply. Confirm the green Alive LED starts blinking. Turn off the power to the module.

4) Attach the RS485 +, - and shield wires to the A8911-23 module. Attach the other end of the RS485 line to the
Modbus master device, such as an AcquiSuite. Be careful to observer polarity on both ends of the RS485
connection. RS485 wiring runs should be limited to 4000 ft.

Page 5 A8911-23

5) Set the Modbus address dipswitches and baud rate dipswitch. For more information on the switch options, see the
section below for configuration.

6) Turn on the power supply. Confirm the green Alive LED starts blinking. Also check the RS485 yellow LEDs.

- If the A8911-23 receives any Modbus traffic on the RS485 port, the yellow RX led should blink.

- If the A8911-23 receives a Modbus query that is addressed to it specifically, the yellow TX LED should blink and
it will respond to the query.

If you are using an AcquiSuite Data Acquisition Server, the A9811-23 should appear in the Modbus device list after
about 2 minutes. Click on the device, and select “Configure” to give the A8911-23 a logical name. This will allow
the AcquiSuite to begin logging data for the device.

7) With the power disconnected, attach the pulse input lines to the pulse terminals. Each pulse input should have a
GND and a P# terminal. If the pulse output device is polarity sensitive, attach the pulse – terminal to the A8911-23
GND terminal, and the pulse + terminal to the A8911-23 P# terminal. The A8911-23 provides 3-5 volts on the P#
terminal for sensing. The remote pulse output device must not supply voltage to the terminals.

Wiring runs to pulse input terminals should be kept as short as possible. Wiring runs longer than 200 ft should be
avoided. Wiring should avoid proximity to sources of electrical noise such as running in parallel to electrical
cable, and VFD systems.

8) Power up the A8911-23. The Input LEDs for each connected input should now blink. The input LED will be on
when the contacts are closed.

WARNING: After wiring the A8911-23, remove all scraps of wire or foil shield from the electrical panel. This
could be dangerous if wire scraps come into contact with high voltage wires.

Configuration

Modbus Address: Before the A8911-23 can be used, you must set the Modbus address of
the A8911-23. This address must be unique among all Modbus devices in the system. The
A8911-23 supports address 1 through 127.

Select an address, and set the dipswitches to match.

The sum of the value of the switches is the address. In the example to the right, address 52
is set by placing switch 4, 16 and 32 to the on position.

Note: 4 + 16 + 32 = 52

Baud Rate: This option sets the serial port speed for the RS485 port. Set this option to
“off” for 19200. Set the switch to “on” for 9600 baud.

Operation

The device should power up and be ready in a few seconds. The LEDs should blink in the following manner.

● The green "Alive" LED should start to blink approximately once per second.

● The yellow RS485 TX and RX LEDs will blink for local Modbus activity.

● The red input status LEDs will blink when input contact closures are detected. Input status LEDs are adjacent to the

corresponding input screw terminals.

If the A8911-23 is attached to an AcquiSuite Data Acquisition Server, you will need to configure each pulse input with a
Name, Engineering Unit, and Multiplier.

Page 6 A8911-23

Troubleshooting

Pulse count not incrementing:

Check the input LED for the specific input that is not working. The LED should blink when the pulse meter closes the
contact output. If th not blinking, try bridging the input terminals with a short piece of wire to confirm the LED comes on .

Try bridging the terminals at the other end of the pulse wiring run. This will confirm there are no breaks in the wire.

Verify the pulse output device is operating.

Disconnect the A8911-23 input and use a hand held digital meter and measure resistance of the pulse output device. Verify
that the pulse output device is operational and the contact closure reads less than 1000 ohms when closed. For high
resistance pulse devices such as intrinsic barriers, the “contact closure threshold” register may need to be configured to a
larger value. The default is 1k however up to 2.5k is allowed. If using the AcquiSuite data acquisition server, use the
advanced configuration page of the A8911-23 in the Modbus/device list to set this option.Modbus registers

Register Listing

The A8911-23 responds to the following Modbus/RTU functions:

0x11 Report slave id.

0x03 read holding registers (multiple)
0x06 preset single register

All Modbus registers are read-only unless otherwise noted. Registers listed as “NV” are options that are stored in non­volatile memory and will be preserved when power is removed from the device.
Modbus 40xxx registers (read registers)

Data points:

------- ------- ------- -----------------­offset point type desc

0 40001 UINT32 pulse count 1 MSW (NV Mem, all pulse counts)
1 40002 UINT32 pulse count 1 LSW
2 40003 UINT32 pulse count 2 MSW
3 40004 UINT32 pulse count 2 LSW
4 40005 UINT32 pulse count 3 MSW
5 40006 UINT32 pulse count 3 LSW
6 40007 UINT32 pulse count 4 MSW
7 40008 UINT32 pulse count 4 LSW
8 40009 UINT32 pulse count 5 MSW
9 40010 UINT32 pulse count 5 LSW
10 40011 UINT32 pulse count 6 MSW
11 40012 UINT32 pulse count 6 LSW
12 40013 UINT32 pulse count 7 MSW
13 40014 UINT32 pulse count 7 LSW
14 40015 UINT32 pulse count 8 MSW
15 40016 UINT32 pulse count 8 LSW
16 40017 UINT32 pulse count 9 MSW
17 40018 UINT32 pulse count 9 LSW
18 40019 UINT32 pulse count 10 MSW
19 40020 UINT32 pulse count 10 LSW
20 40021 UINT32 pulse count 11 MSW
21 40022 UINT32 pulse count 11 LSW
22 40023 UINT32 pulse count 12 MSW
23 40024 UINT32 pulse count 12 LSW
24 40025 UINT32 pulse count 13 MSW
25 40026 UINT32 pulse count 13 LSW
26 40027 UINT32 pulse count 14 MSW
27 40028 UINT32 pulse count 14 LSW
28 40029 UINT32 pulse count 15 MSW
29 40030 UINT32 pulse count 15 LSW
30 40031 UINT32 pulse count 16 MSW
31 40032 UINT32 pulse count 16 LSW

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32 40033 UINT32 pulse count 17 MSW
33 40034 UINT32 pulse count 17 LSW
34 40035 UINT32 pulse count 18 MSW
35 40036 UINT32 pulse count 18 LSW
36 40037 UINT32 pulse count 19 MSW
37 40038 UINT32 pulse count 19 LSW
38 40039 UINT32 pulse count 20 MSW
39 40040 UINT32 pulse count 20 LSW
40 40041 UINT32 pulse count 21 MSW
41 40042 UINT32 pulse count 21 LSW
42 40043 UINT32 pulse count 22 MSW
43 40044 UINT32 pulse count 22 LSW
44 40045 UINT32 pulse count 23 MSW
45 40046 UINT32 pulse count 23 LSW

System information points:

------- ------- ------- -----------------­offset point type description

1000 41001 UINT16 Serial Number (bytes 1,2) (our serial number)
1001 41002 UINT16 Serial Number (bytes 3,4)
1002 41003 UINT16 Serial Number (bytes 5,6)
1003 41004 UINT16 firmware version major
1004 41005 UINT16 firmware version minor
1005 41006 UINT32 mfg date MSW
1006 41007 UINT32 mfg date LSW
1007 41008 UINT32 up time (seconds) MSW.
1008 41009 UINT32 up time (seconds) LSW.
1009 41010 UINT16 Our modbus address
1010 41011 UINT16 Hardware Version major (8911)
1011 41012 UINT16 Hardware Version minor. HighByte=pcb-rev(0=rev A, etc),

lowbyte = part-rev (0=rev A, etc)

1012 41013 UINT16 (NV/r/w) contact closure threshold in ohms, default 1000 =

1kohm. 100-2550 ohms allowed.

1013 41014 UINT16 (NV/r/w) contact closure speed, pulse speed:

0=10hz/default, 1=50hz, 2=100hz

1014 41015 UINT16 (NV/r/w) Pulse KYZ flag bitmap. channels 1-16 0x01 =

pulse1 kyz mode, 0x02 = p2, etc.
1015 41016 UINT16 (NV/r/w) Pulse KYZ flag bitmap. channels 17-23
1016 41017 UINT16 power supply voltage monitor. scale: x100
1017 41018 UINT16 pcb temperature monitor. scale: x100
1018 41019 UINT16 5V internal power supply voltage monitor. scale: x100
1019 41020 UINT16 RS485 baud rate. 2=9600, 3=19200.
1020 41021 UINT16 reason for reboot. 0x01=POR, 0x02=EXTR 0x04=WDTR

0x08=BODR, 0x8000=WDTOF

Modbus function 0x11 Slave ID response will report the following:

"Obvius, A8911-23, pulse counter, 23 channel", id=47

Page 8 A8911-23

Register Functions

Pulse Count: The pulse count is stored as an unsigned 32bit integer. This allows for 2^32 pulses (4.2billion) to be counted
before rollover. On Modbus systems that do not allow you to read 32bit values, you can calculate the pulse count as follows:

count = (MSW * 65536) + LSW

or

count = (MSW << 16) | LSW [bit shift high order word by 16 bits and xor against low order word ]

Pulse count registers accumulate a total number of pulses received on each pulse input. The pulse count totals always
increment and can not be cleared or set to an arbitrary value to prevent tampering. All pulse count totals are stored in non­volatile memory to preserve counts during power failure. The unsigned 32 bit counter values can accumulate up to 4.29
billion (2^32) pulses before rollover.

All 32 bit data point values are encoded in 2 Modbus registers (16bits each). Modbus master systems should always query
the A8332-8F2D using a single query to read an entire block of registers. Never use two queries to read one register and
then combine the two results into a single 32 bit value. Doing so will allow the pulse count to increment in the middle of the
two Modbus queries, and will cause intermittent data readings that are incorrect.

For example, a pulse input has a count of 65534. This is represented as a 32 bit hex number 0x0000FFFE. The first 4 digits
are the MSW register, the second 4 digits are the LSW register. The Modbus Master reads the first (MSW) register and gets
0x0000. In between the two readings, the pulse input counts 2 more pulses, making the total 65536 or 0x00010000 in hex.
Next the Master reads the second (LSW) register and gets 0x0000. When the two registers are combined, the result is
0x00000000. The proper way to handle this situation is to simply read both registers in a single Modbus query.

Page 9 A8911-23

Mechanical Drawings

GND
P1

GND
P2

GND
P3

GND
P4

GND
P5

GND
P6

GND
P7

GND
P8

GND
P9

GND
P10

GND
P11

GND
P12

GND
P13

GND

P14

GND

P15

GND

P16

GND

P17

GND

P18

GND

P19

GND

P20

GND

P21

GND

P22

GND

P23

485 ­485 +

NC

Shield

+24V

GND

P1

Alive

485 TX

485 RX

P2P3P4P5P6P7P8P9

P10

P11P12

P13

P14

P23P22P21P20P19P18P17P16P15

1 2 3 4 5 6 7 8

A8911-23

Rev B

3.39in
86mm

4.13in

105mm

1.18in

30mm

DIN-Rail (EN50022) mount package: Width 105mm (6 modules)

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