Vaisala CARBOCAP GMW80 Series User manual

M212445EN-A
Quick Guide
Vaisala CARBOCAPâCarbon Dioxide
and Temperature Transmitter
GMW87M

PUBLISHED BY
Vaisala Oyj
Vanha Nurmijärventie 21, FI-01670 Vantaa, Finland
P.O. Box 26, FI-00421 Helsinki, Finland
[phone]
Visit our Internet pages at www.vaisala.com.
© Vaisala 2020
No part of this document may be
reproduced, published or publicly
displayed in any form or by any means,
electronic or mechanical (including
photocopying), nor may its contents be
modified, translated, adapted, sold or
disclosed to a third party without prior
written permission of the copyright holder.
Translated documents and translated
portions of multilingual documents are
based on the original English versions. In
ambiguous cases, the English versions are
applicable, not the translations.
The contents of this document are subject
to change without prior notice.
Local rules and regulations may vary and
they shall take precedence over the
information contained in this document.
Vaisala makes no representations on this
document’s compliance with the local
rules and regulations applicable at any
given time, and hereby disclaims any and
all responsibilities related thereto.
This document does not create any legally
binding obligations for Vaisala towards
customers or end users. All legally binding
obligations and agreements are included
exclusively in the applicable supply
contract or the General Conditions of Sale
and General Conditions of Service of
Vaisala.

Table of contents
Product overview...............................................................................................3
Transmitter parts..........................................................................................................................3
Safety..............................................................................................................................................4
Regulatory compliances............................................................................................................ 4
Installation...........................................................................................................5
Wiring............................................................................................................................................. 6
Modbus communication...................................................................................7
Troubleshooting........................................................................................................................... 8
Modbus reference..............................................................................................9
Function codes.............................................................................................................................9
Data encoding.............................................................................................................................. 9
32-bit floating point format..............................................................................................9
16-bit integer format...........................................................................................................9
Modbus registers........................................................................................................................10
Measurement data registers........................................................................................... 10
Status registers...................................................................................................................10
Test value registers............................................................................................................. 11
Device identification objects....................................................................................................11
Modbus communication example..........................................................................................12
Technical data................................................................................................... 13
Warranty.............................................................................................................15
Technical support.............................................................................................15
Recycling............................................................................................................ 15
1

2 M212445EN-A

Product overview
Vaisala CARBOCAPâCarbon Dioxide and Temperature Transmitter GMW87M is a wall-mount
transmitter designed to fulfill the needs for CO2measurements in demanding conditions (for
example, dusty or humid installation locations).
GMW87M can be accessed with the Modbus RTU protocol over an RS-485 interface. The
communication settings for the protocol are entered with DIP switches on the GMW87M
component board.
For information on measurement performance and technical specifications of the transmitter,
see Technical data (page 13).
Transmitter parts
6
7
8
5
3
2
1
4
Figure 1 GMW87M transmitter parts
1DIP switches for Modbus settings
2Screw terminals. The screw terminal block is detachable for easy installation.
3Transmitter cover with captive screws (4 pcs)
4GM10 carbon dioxide measurement module
5Mounting base
6Screw holes for mounting on top and bottom of mounting base (2 screws, Ø 3.5 mm)
7Alternative lead-through for wiring through the back
8Cable gland for leading wires inside the enclosure
3

In GMW87M, the component board is located on the cover of the enclosure. Wires are led into
the enclosure either through a cable gland on the bottom of the mounting base or a sealed
lead-through at the back. The enclosure is opened and closed with 4 screws.
Safety
The GMW87M transmitter delivered to you has been tested for safety and approved as shipped
from the factory. Note the following precautions:
Make sure that you prepare or connect only de-energized wires.WARNING!
Do not modify the unit or use it in ways not described in the
documentation. Improper modification or use may lead to safety hazards,
equipment damage, failure to perform according to specification, or decreased
equipment lifetime.
CAUTION!
Electrostatic Discharge (ESD) can cause immediate or latent
damage to electronic circuits. Avoid touching exposed component contacts
during installation and maintenance.
CAUTION!
Regulatory compliances
Vaisala GMW80 series transmitters are in conformity with the provisions of the following EU
directives:
• RoHS Directive
• EMC Directive
The conformity is declared with using the following standards:
• EN 50581: Technical documentation for the assessment of electrical and electronic
products with respect to the restriction of hazardous substances.
• EN 61326-1: Electrical equipment for measurement, control, and laboratory use – EMC
requirements – Immunity test requirements for equipment intended to be used in an
industrial electromagnetic environment.
• EN 55032: Information technology equipment – Radio disturbance characteristics – Limits
and methods of measurement.
4 M212445EN-A

Installation
The GMW87 transmitter is designed to be installed on a mounting box or directly to a wall
surface. For transmitter dimensions, see Figure 3 (page 6).
220
HFT
545
VS
SCREW TERMINAL WIRING
D
D
RS GND
4
2
1
3
Figure 2 Mounting GMW87M
1Cable gland for leading the input/output cable (Ø 4 ... 8 mm) inside the enclosure
2Alternative lead-through for wiring through the back (break seal and transfer cable gland
to the threads on this lead-through)
3Wiring instructions label
4Mounting screws (2 pcs, Ø 3.5 mm, head Ø ≤8 mm)
1. Open the transmitter cover (4 screws) and use 2 mounting screws (Ø 3.5 mm) to attach
the mounting base to the installation surface. Point the cable gland straight down.
2. Route the input/output cable through the cable gland.
If you use the alternative lead-through on the back of the transmitter, seal
the hole on the bottom of the transmitter after removing the cable gland.
3. For ease of installation, you can disconnect the screw terminal block by pulling it out from
the component board.
4. Attach wiring to the screw terminals as shown on the wiring instructions label. See also
Wiring (page 6).
5. If you disconnected the screw terminal block, plug it back in. Make sure it is positioned
correctly.
5

6. Push down gently on the GM10 module. The module should be straight and firmly
connected.
7. Tighten the cable gland and close the transmitter cover (4 screws).
Mounting bases are tailored to the individual transmitter at the
factory. If you attach several mounting bases before connecting the transmitters,
store the transmitters in their original shipping boxes, so that you can match the
serial number on the mounting base to the serial number on the shipping box.
CAUTION!
41
84
164
120
Ø 3.5
134
mm
Figure 3 GMW87M dimensions
Wiring
D
RS
GMW87M
18 ... 35 VDC
or 20 ... 30 VAC
Power supply
Controller
RSGND
D
GND
VS
VS
RS-485
RS-485
isolated
Leave the bottom terminal
in GMW87M unconnected
Figure 4 GMW87M wiring diagram
6 M212445EN-A

Modbus communication
The Modbus variant used in GMW87M is Modbus RTU. For a list of the Modbus registers
available in GMW87M, see Modbus registers (page 10).
You can use up to 8 transmitters on the same RS-485 line. You must configure each transmitter
on the line to have a dierent Modbus address.
Before taking the transmitter into use, check that the Modbus device address, bit
rate setting, and parity setting match the settings in your system.
The number of stop bits is not significant. The device supports automatically both
1 and 2 stop bits.
3
D
RS
D
GND
VS
VS
1
2
5
6
4
Figure 5 GMW87M component board with DIP switches and screw terminals
1DIP switches for setting the GMW87M Modbus device address
2DIP switches for selecting Modbus communication bit rate and parity (N/E)
3Screw terminal not used in GMW87M
4Switch for 120 Ω RS-485 bus termination. Switch RS-485 bus termination ON only on the
last device of the wiring if there is no separate terminator on the bus.
5RS-485 (Modbus) screw terminals
6Power supply input (18 … 35 VDC or 20 … 30 VAC) screw terminals
Make selections with the DIP switches by sliding the DIP switch to the right (ON). Keep the
other DIP switches on the left position (OFF).
7

Setting Modbus device address with DIP switches
Figure 6 Modbus device address DIP switch
example
DIP
switches 32,
8, and 1 set
to ON
The Modbus device address
is encoded in eight bit
binary form, with each
numbered switch
representing a single bit.
This example shows
address 41 selected: DIP
switches 32, 8, and 1
(decimal: 41, binary:
00101001) are set to ON.
Modbus device address ranges
The Modbus device address range for the transmitter is 1 … 247. Up to 255 is possible, but non-
standard.
If no address is selected (0), the device is o-line and will not respond to any Modbus
requests.
Troubleshooting
If you experience problems with GMW87M, first see the following table concerning the behavior and
error indications of the transmitter.
Table 1 Troubleshooting table
Problem Solution
The device is not responding • Power-cycle the transmitter by disconnecting the screw
terminal block
• Check power supply voltage
• Check wiring, including RS-485 bus polarity
• Check that RS GND is connected between the transmitter and
the receiver
• Compare the DIP switch settings to your Modbus host settings
• Check that RS-485 termination is enabled only on the last
device of the wiring
• Alternatively, try operation without RS-485 termination at all
Unexpected value in Modbus
response
• Change register number and/or data encoding settings in your
Modbus host system
No measurement result and/or
non-zero status code returned
• Device is warming up, try again after 20 seconds
• Power-cycle the transmitter by disconnecting the screw
terminal block
• Check that the GM10 module is properly attached
• Contact Vaisala for a replacement GM10 module
If you cannot locate the source of the error and return the transmitter to operational state,
contact Vaisala technical support. See Technical support (page 15).
8 M212445EN-A