HTP 7350P-629 User manual

120 Braley Rd. P.O. Box 429 East Freetown, MA 02717-0429 www.htproducts.com
LP-372 Rev. 6.14.13
MODBUS
INSTALLATION
TROUBLESHOOTING
MOD BUS Models
7350P-629
FOR USE WITH MODCON, MODCON VWH, PIONEER, VERSA-FLAME
MANUFACTURED ON OR AFTER JULY 1, 2011
FOR USE WITH ELITE, ELITE VWH
MANUFACTURED ON OR AFTER AUGUST 1, 2011
NOTICE: HTP reserves the right to make product changes or updates without notice and will not be held liable for typographical errors
in literature.
NOTE TO CONSUMER: PLEASE KEEP ALL INSTRUCTIONS FOR FUTURE REFERENCE.

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The following defined terms are used throughout this manual to bring attention to the presence of hazards of various risk
levels or to important information concerning the product.
DANGER indicates an imminently hazardous situation which, if not avoided, will result in death or serious injury.
WARNING indicates a potentially hazardous situation which, if not avoided, could result in death or serious injury.
CAUTION indicates a potentially hazardous situation which, if not avoided, may result in minor or moderate injury.
CAUTION used without the safety alert symbol indicates a potentially hazardous situation which, if not avoided, may result in property
damage.
FOREWORD
This manual provides guidelines for the use and installation of the Modbus communication system with HTP appliances.
FOR THE INSTALLER
The installer should be guided by the instructions furnished with the Modbus, local codes and utility company requirements. Preference
should be given to codes and requirements where they differ from the furnished instructions.
Additional publications which should guide the installer include:
The latest version of the National Electrical Code, NFPA No. 70.
In Canada, refer to Canadian Electrical Code C 22.1, from Canadian Standards Association, 5060 Spectrum Way, Suite 100,
Mississauga, Ontario, Canada L4W 5N6.
TABLE OF CONTENTS
PART 1 - GENERAL INFORMATION..........................................................................................................................................3
A. WHAT’S IN THE BOX.................................................................................................................................................................4
B. MINIMUM SYSTEM REQUIREMENTS......................................................................................................................................4
C. DEFINITIONS.............................................................................................................................................................................4
PART 2 - INSTALLATION ...........................................................................................................................................................5
A. WIRING REQUIREMENTS ........................................................................................................................................................5
B. JUMPER SETTING ....................................................................................................................................................................6
PART 3 –COMMUNICATION CONFIGURATION (APPLIANCES WITH A 3 CHARACTER RED LED DISPLAY) ..................7
A. MODBUS ENABLE.....................................................................................................................................................................7
B. MODBUS ADDRESS..................................................................................................................................................................7
C. BAUD RATE...............................................................................................................................................................................7
D. PARITY AND STOP BITS..........................................................................................................................................................8
PART 4 –COMMUNICATION CONFIGURATION (APPLIANCES WITH AN LCD TEXT DISPLAY).........................................8
A. MODBUS ENABLE.....................................................................................................................................................................8
B. MODBUS ADDRESS..................................................................................................................................................................8

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C. BAUD RATE...............................................................................................................................................................................9
D. PARITY AND STOP BITS..........................................................................................................................................................9
PART 5 –GENERAL MODBUS INFORMATION........................................................................................................................9
A. DATA TRANSMISSION MODE..................................................................................................................................................9
B. MODBUS BOARD DIAGNOSTICS.............................................................................................................................................9
C. MODBUS COMMUNICATION..................................................................................................................................................10
D. MODBUS FUNCTION SET......................................................................................................................................................10
E. MODBUS EXCEPTION CODES ..............................................................................................................................................11
PART 6 - REGISTER MAP........................................................................................................................................................11
A. PRIMARY DATA TABLES........................................................................................................................................................11
B. APPLIANCE MEMORY MAP....................................................................................................................................................11
C. BLOCKING CODES.................................................................................................................................................................13
D. LOCKOUT CODES ..................................................................................................................................................................14
E. STATUS CODES......................................................................................................................................................................14
F. CONFIGURATION BITS...........................................................................................................................................................14
PART 7 - APPLIANCE OPERATION.........................................................................................................................................15
A. APPLIANCE OPERATION WITH MODBUS COMMUNICATIONS ..........................................................................................15
B. EXAMPLE #1............................................................................................................................................................................15
C. EXAMPLE #2 ...........................................................................................................................................................................15
1. SEND FIRING RATE COMMAND FROM MASTER....................................................................................................................15
2. SEND TEMPERATURE COMMAND FROM MASTER................................................................................................................16
D. EXAMPLE #3 –HOT WATER GENERATION .........................................................................................................................16
E. CASCADE................................................................................................................................................................................16
F. RATE AND TEMPERATURE CONVERSIONS ........................................................................................................................17
G. APPLIANCE STATUS CODES................................................................................................................................................19
PART 8 - TROUBLESHOOTING...............................................................................................................................................19
A. PHYSICAL LAYER...................................................................................................................................................................19
B. COMMUNICATIONS................................................................................................................................................................19
C. LED DIAGNOSTICS.................................................................................................................................................................19
D. MODBUS ERROR CODES......................................................................................................................................................19
INSTALLATION AND MAINTENANCE NOTES..............................................................................................................................20
HTP CUSTOMER INSTALLATION RECORD FORM......................................................................................................................21
PART 1 - GENERAL INFORMATION
Modbus communication systems utilize a master-follower format where connected HTP appliances follow commands from a building
management system or other Modbus master device linked over an RS-485 serial connection.
If any system component(s) is/are exposed to the following, do not operate until the affected component(s) has/have been inspected by
a qualified serviceman.
1. FIRE
2. DAMAGE
3. SUBMERSION IN WATER

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Any claims for damage or shortage in shipment must be filed immediately against the transportation company by the consignee.
A. WHAT’S IN THE BOX
1. One MODBUS Adapter
2. One bag of mounting hardware
3. One mounting template
B. MINIMUM SYSTEM REQUIREMENTS
1. A Modbus master device, such as a Building Automation System (BAS) or computer with Modbus master software, and an RS-485
serial port or USB port with a converter to RS-485.
2. HTP Modbus adapter (this kit), and an HTP appliance/water heater equipped with a control with firmware revision MTSA-P110414 or
greater. To determine whether your product is compatible with this adapter, refer to Figure 1.
3. Shielded twisted pair communication cable.
Figure 1 –Controller Revision Label Location
C. DEFINITIONS
Table 1 is a list of definitions used throughout this manual.
ABBREVIATION OR ACRONYM
DEFINITION
ASCII
American Standard Code for Information Interchange
BAS
Building Automation System
Baud (Baud Rate)
Number of data bits transmitted per second (bps)
BMS
Building Management System
EMS
Energy Management System
FDX
Full-Duplex
HDX
Half-Duplex
Hex
Hexadecimal Number (0-9, A-F)
I/O Box
Input/Output
LSB
Least Significant Byte

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Modbus
A serial, half-duplex transmission protocol developed by AEG Modicon
MSB
Most Significant Byte
RS232
RS232 serial, full-duplex (FDX) transmission of data standard
RS485
RS-485 serial transmission of data standard
RTU
Remote Terminal Unit
PG
Industry Standard liquid-tight wiring entry connector
MB
MODBUS
Table 1 –Acronym definitions
PART 2 - INSTALLATION
The Modbus adapter should be mounted to a solid surface. The adapter has two tabs with four mounting holes designed specifically for
this purpose.
Use the mounting screws provided with the adapter. Damage to Modbus adapter or appliance due to installation with other mounting
screws IS NOT covered by warranty.
When mounting the unit, keep in mind that the top cover must be removed to connect the Modbus communication cable, and that the
appliance communication wire must reach the control inside the appliance.
The Modbus adapter can be mounted on the side of the appliance OR the wall next to the appliance, as long as care is taken to avoid
components behind the mounting surface. The mounting location must be within 3 feet of the appliance controller in order to be plugged
into the controller programming port.
NOTE: It is not recommended to install the Modbus adapter inside the appliance housing. Doing so may affect appliance operation or
damage the Modbus adapter.
Damage to Modbus adapter or appliance due to improper installation IS NOT covered by warranty.
A. WIRING REQUIREMENTS
RS-485 Communication Bus
Maximum length: 1000 feet
Cable specification: 24 AWG / A,B (twisted pair) and GND shielded, with characteristic impedance: 120 ohm
Maximum load: 32 units (32 nodes)
Wires will be passed through the PG connector on the side of the adapter, then connected to the three position connector marked “X5”
on the circuit board inside the adapter. A label is provided inside the adapter to ensure proper connections of A, B, and GND. Two wires
(MB IN and MB OUT) may be attached to each X5 screw.
See Figure 2 for an example wiring diagram.

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BMS
APPLIANCE X
X5X5
B
A
G
REMOVE JUMPER
(J1) FROM THIS
ADAPTER ONLY!
MODBUS ADAPTER
APPLIANCE 1
X5
Figure 2 –Jumper Configurations in a Modbus Network
B. JUMPER SETTING
The appliance display handles most of the Modbus adapter configuration. There is one jumper on the Modbus adapter. When this
jumper is in place (factory default) it connects a termination resistor across the data lines of the RS-485 connection. Leave the jumper
in if the Modbus adapter is at the end of the RS-485 bus. Remove the jumper if the Modbus adapter is one of many connections and
not at the end of the bus. See Figures 2 and 3.
Figure 3 –Modbus Termination Jumper Location (Highlighted in Grey)

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PART 3 –COMMUNICATION CONFIGURATION (APPLIANCES WITH A 3
CHARACTER RED LED DISPLAY)
A. MODBUS ENABLE
1. Press and hold ENTER and RESET simultaneously. Use the UP and DOWN arrows to show 925 on the display, then press and hold
ENTER to enter the installer menu.
2. Once in the Installer Menu, use the ENTER button to navigate to Parameter 37. When at Parameter 37, use UP or DOWN select the
desired setting from the table below:
Parameter
Setting
Description
37
0
MODBUS “DISABLED” (factory default)
37
1
MODBUS “ON”
37
2
MODBUS “AUTO” (enables automatic detection of a PC or Adapter)
Table 2 –Parameter 37 Settings
Please do not leave the Installer Menu after making this selection. Configure the Address, Baud Rate, and Parity settings described
below.
B. MODBUS ADDRESS
NOTE: Modbus must be enabled on the appliance as outlined above for the following parameters to be viewed and changed.
The Modbus address space is comprised of 256 addresses. These are defined as follows:
Address 0 is a broadcast address. The master can send data to address 0 and all followers will process the data.
Addresses 1 –247 are free to be assigned to Modbus devices on the bus. Each address can be assigned to only one Modbus
device on the bus.
Addresses 248 –256 are not available for use.
MODBUS ADDRESSING SUGGESTIONS*
Each device must have a unique address.
It is not recommended to use 1 as an address, as this is often the default address for various other Modbus devices
that may be on the bus.
In order to keep track of addresses for future maintenance purposes, record all device addresses in the Installation
and Maintenance Notes section included in this manual.
*SAVE THIS DOCUMENT IN A SECURE LOCATION FOR FUTURE REFERENCE.
To set the Modbus adapter address in the appliance installer menu:
From the Installer Menu, press the ENTER key to advance to Parameter 38. Use the UP and DOWN arrows to set the desired address.
Press the RESET button to store the address.
Press the DOWN button to advance to Parameter 39 - Baud Rate.
C. BAUD RATE
The baud rate (communication speed) can be set to either 9600 or 19200 baud. All HTP appliances, as well as any other device on the
same bus and the Modbus master, must have the same baud rate setting. Select the highest baud rate that offers the most reliable
communication performance over the bus.
Some things that can affect communications are:
Long wire runs
Wire quality
A noisy electrical environment
The number of devices on the bus.
These conditions may require using a lower baud rate.
Use the UP and DOWN buttons to select the desired setting from the table below:
Parameter
Setting
Description
39
0
BAUD RATE = 9600 (factory default)
39
1
BAUD RATE = 19200
Table 3 –Parameter 39 Settings
Press RESET to store the baud rate. Press the DOWN button to advance to Parameter 40 - Parity and Stop Bits.

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D. PARITY AND STOP BITS
The parity/stop bits parameter of the Modbus adapter must be set to match the rest of the devices on the bus. Although it is common to
set serial devices to use no parity, setting the parity to even or odd may improve communications reliability on all connected devices on
the bus.
This parameter has 4 possible selections which should be sufficient to establish communication with other devices. These selections
are outlined in Table 4.
Parameter
Setting
Description
40
0
No parity 1 stop bit (factory default)
40
1
No parity 2 stop bits
40
2
Even parity 1 stop bit
40
3
Odd parity 1 stop bit
Table 4 –Parameter 40 Settings
Press and Hold the RESET button to store all parameters and exit the Installer Menu.
PART 4 –COMMUNICATION CONFIGURATION (APPLIANCES WITH AN LCD TEXT
DISPLAY)
A. MODBUS ENABLE
1. Press and hold the ENTER key until you see the screen at right.
Use the RIGHT arrow to select a character, then use the UP and DOWN arrows to
select the desired character value. RIGHT arrow over to the next character and repeat the selection. Once you have 925 on the screen,
press and hold ENTER on the display to enter the Installer Menu.
2. Once in the Installer Menu, use the RIGHT arrow to navigate to Parameter 37. When at Parameter 37, press ENTER. The current
setting should be flashing. Press UP or DOWN to select the desired setting from Table 5:
Parameter
Setting
Description
37
OFF
MODBUS “DISABLED” (factory default)
37
ON
MODBUS “ON”
37
AUTOMATIC
MODBUS “AUTO” (enables automatic detection of a PC or Adapter)
Table 5 –Parameter 37 Settings
FUNCTION 37 Press ENTER once the desired setting is flashing on the display. Once accepted, the
selection should not flash.
Please do not leave the Installer Menu. Configure the Address, Baud Rate, and Parity settings described below.
B. MODBUS ADDRESS
NOTE: Modbus must be enabled on the appliance as outlined above for the following parameter to be viewed and changed.
The Modbus address space is comprised of 256 addresses. These are defined as follows:
Address 0 is a broadcast address. The master can send data to address 0 and all followers will process the data.
Addresses 1 –247 are free to be assigned to Modbus devices on the bus. Each address can be assigned to only one Modbus
device on the bus.
Addresses 248 –256 are not available for use.
MODBUS ADDRESSING SUGGESTIONS*
Each device must have a unique address.
It is not recommended to use 1 as an address, as this is often the default address for various Modbus devices.
In order to keep track of addresses for future maintenance purposes, record all device addresses in the Installation
and Maintenance Notes section, included in this manual.
*SAVE THIS DOCUMENT IN A SECURE LOCATION FOR FUTURE REFERENCE.
In the Installer Menu, press RIGHT to advance to Parameter 38.
FUNCTION 38 Press ENTER. The address value will blink. Use the UP and DOWN arrows to set the
desired address. Press ENTER again to accept your selection (and stop the display from
ENTER MENU CODE
925
MODBUS MODE
OFF 37
MODBUS ADDRES
0 38

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blinking).
Press the RIGHT button to advance to Parameter 39 - Baud Rate.
C. BAUD RATE
The baud rate (communication speed) can be set to either 9600 or 19200 baud. All HTP appliances, as well as any other device on the
same bus and the Modbus master, must have the same baud rate setting. Select the highest baud rate that offers the most reliable
communication performance over the bus.
Some things that can affect communications are:
Long wire runs
Wire quality
A noisy electrical environment
The number of devices on the bus
These conditions may require using a lower baud rate.
FUNCTION 39 Press ENTER. The baud rate number will blink. Use the UP and DOWN arrows to toggle
between 009600 and 019200. Press ENTER again to select the baud rate and stop the
display from blinking.
Press DOWN to advance to Parameter 40 - Parity and Stop Bits.
D. PARITY AND STOP BITS
The parity/stop bits parameter of the Modbus adapter must be set to match the rest of the devices on the bus. Although it is common to
set serial devices to use no parity, setting the parity to even or odd may improve communications reliability on all connected devices on
the bus.
This parameter has 4 possible selections which should be sufficient to establish communication with other devices. These selections
are outlined in Table 6.
PARAMETER 40 SETTING TEXT DISPLAY
PARITY / STOP BITS
1 ST
No parity 1 stop bit
2 ST
No parity 2 stop bits
E PA
Even parity 1 stop bit
O PA
Odd parity 1 stop bit
Table 6 –Parameter 40 Settings
FUNCTION 40 Press ENTER. The STOP/PARITY value will blink. Use the UP and DOWN arrows to
toggle between 1 ST, 2 ST, E PA, and O PA. Make your selection based on the table
above. Press ENTER again to select the STOP/PARITY value and stop the display from
blinking.
Configuration is now complete. Press RESET to permanently store ALL the Modbus settings.
PART 5 –GENERAL MODBUS INFORMATION
A. DATA TRANSMISSION MODE
Many Modbus master devices can be configured to transmit data in either RTU or ASCII modes. Since RTU messages use fewer data
bits and are more efficient, RTU has been chosen for all communication with the Modbus adapter. Please ensure that the master
device is configured for RTU communications.
B. MODBUS BOARD DIAGNOSTICS
The Modbus board is equipped with three LEDs for visual diagnostics: Two yellow and one green. These LEDs are located under the
Modbus cover. One yellow LED (D5) is used to indicate reception of data. The other yellow LED (D6) is used to indicate transmission of
data. The green LED (D7) shows internal faults. See Figure 4 for LED locations.
Internal Faults (Green LED):
Normal Operation = 1 second on, 1 second off
Controller Fault = Continuously on
No Burner Control Communication = 0.5 seconds on, 1.5 seconds off
No Modbus Communication = 1.5 seconds on, 0.5 seconds off
MODBUS SPEED
009600 39
MODBUS STOP/PARITY
1 ST 40

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Figure 4 –Modbus Diagnostic LEDs
C. MODBUS COMMUNICATION
The Modbus communication commands can be found in Parts 3 and 4 of this manual, and exception codes supported by the
communication board can be found in Part 5, Section E.
D. MODBUS FUNCTION SET
FUNCTION
SUB FUNCTION
HEX
DESCRIPTION
DEC
HEX
DEC
1
01
Read coil status
2
02
Read input status
3
03
Read holding registers
4
04
Read input registers
5
05
Force single coil
6
06
Preset single register
7
07
Read exception status
8
08
0
00
Diagnostic –Return query data
1
01
Diagnostic –Restart communication
2
02
Diagnostic –Return diagnostic register
4
04
Diagnostic –Force listen mode
10
0A
Diagnostic –Clear counters and diagnostic registers
11
0B
Diagnostic –Return bus message count
12
0C
Diagnostic –Return bus exception error count
13
0D
Diagnostic –Bus exception error count
14
0E
Diagnostic –Return follower message count
15
0F
Diagnostic –Return communication error count
16
10
Diagnostic –Return follower NAK count