HTP 7350P-636 User manual

MODBUS / BACnet Adapter Installation Instructions
Part # 7350P-636
For Use with BIC-928 Control Based EnduroTI and Elite Premier Boilers (see page 2 to determine compatibility)
BIC-926 Control Based Modcon, Modcon VWH, Pioneer, and Versa Flame Products Manufactured On or After July 1, 2011,
and BIC-926 Control Based Elite, Elite VWH, and Phoenix Water Heaters Manufactured On or After August 1, 2011
272 Duchaine Blvd. New Bedford, MA 02745 www.htproducts.com
lp-548 Rev. 000 Rel. 004 Date 1.11.19
STOP! Follow these instructions or warranty will be void!
The manufacturer reserves the right to make changes or updates without notice and will not be held liable for errors in literature.
NOTE TO CONSUMER: PLEASE KEEP ALL INSTRUCTIONS FOR FUTURE REFERENCE.
NOTE: Contains additional information important to a procedure.
Foreword
This manual provides guidelines for the use and installation of the MODBUS/
BACnet communication system with HTP appliances.
For the Installer
The installer should be guided by the instructions furnished with the
MODBUS/BACnet, local codes and utility company requirements. Preference
should be given to codes and requirements where they dier from the
This manual must only be used by a qualied heating installer / service
technician. Read all instructions in this manual before installing. Failure to
comply could result in property damage or improper appliance operation.
Such damages or service calls to correct operation ARE NOT covered by
warranty.
The following dened terms are used throughout this manual to bring
attention to the presence of hazards of various risk levels or to important
product information.
CAUTION used without the safety alert symbol indicates a potentially
hazardous situation which, if not avoided, may result in property damage.
Table of Contents
Part 1 - General Information 2
A. What’s in the Box 2
B. Minimum System Requirements 2
C. Denitions 2
Part 2 - Installation 2
A. BMS Wiring Requirements 3
B. Jumper Setting 3
Part 3 - Communication Conguration 4
A. MODBUS/BACnet Enable 4
B. MODBUS Address 4
C. BACnet Address 4
D. Baud Rate 5
E. Parity and Stop Bits 5
Part 4 - MODBUS Registers and BACnet Objects 5
A. Primary Data Tables 5
B. Appliance Memory Map 6
C. Conguration Bits 8
Part 5 - Appliance Operation 9
A. Appliance Operation with MODBUS and BACnet
Communications 9
B. Example #1 - Enable / Disable CH and DHW Demand 9
C. Example #2 - Sending DHW Setpoint Via Direct Write Method 9
D. Example #3 - Sending Setpoint or Firing Rate from BMS 9
1. Sending Desired Setpoint from BMS to Appliance Via Simulated 0-10V
Method 9
2. Send Firing Rate Command from BMS to Appliance 10
E. Example #4 - Hot Water Generation 11
F. Cascade 11
G. Temperature Conversions (MODBUS Only) 11
Part 6 - Troubleshooting 12
A. MODBUS/BACnet Board Diagnostics 12
B. Physical Layer 12
C. Communications 12
D. Error Codes 13
E. Appliance 0-7 Status Codes 13
F. Appliance 0 and Appliance 1 Blocking Codes 13
G. Appliance 0-7 Lockout Codes 14
Communication Adapter Limited Warranty 15
Installation and Maintenance Notes 16
furnished instructions.
Additional publications which should guide the installer include:
1. The latest version of the National Electrical Code, NFPA No. 70.
2. In Canada, refer to Canadian Electrical Code C 22.1, from Canadian Standards Association, 5060 Spectrum Way, Suite 100, Mississauga,
Ontario, Canada L4W 5N6.
3. Local, state, provincial, and national codes, laws, regulations, and ordinances.

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One (1) MODBUS / BACnet Adapter
One (1) Bag of Mounting Hardware
One (1) Mounting Template
Ensure all components are included in the shipping crate. Move components to the
installation location. Any claims for damage or shortage in shipment must be led
immediately against the transportation company by the consignee.
CAUTION
If any system components are exposed to the following, do not operate until the
aected components have been inspected by a qualied serviceman.
1. FIRE
2. DAMAGE
3. SUBMERSION IN WATER
Any claims for damage or shortage in shipment must be led immediately against
the transportation company by the consignee.
A. What’s in the Box
1. A MODBUS or BACnet master device, such as a Building Management System
(BMS) or computer with MODBUS or BACnet master software, and an RS-485
serial port or USB port with a converter to RS-485.
2. HTP MODBUS/BACnet adapter (this kit), and an HTP appliance/water heater
equipped with a BIC-926 control with rmware revision MTSA-P110414 or
greater; or an HTP appliance equipped with a BIC-928 control with rmware
revision ARBA-P151112 or greater. To determine whether your BIC-926 based
product is compatible with this adapter, turn o power to the appliance. Then
B. Minimum System Requirements
Abbreviation
or Acronym Denition Abbreviation or Acronym Denition
ASCII American Standard Code for Information Interchange LSB Least Signicant Byte
BACnet
BACnet is a communications protocol for Building Management and
Control networks. It is an ASHRAE, ANSI, and ISO 16484-5 standard
protocol.
MODBUS A serial, half-duplex transmission protocol
developed by AEG Modicon
Baud (Baud Rate) Number of data bits transmitted per second (bps) MSB Most Signicant Byte
BMS Building Management System RS232 RS232 serial, full-duplex (FDX) transmission of
data standard
EMS Energy Management System RS485 RS485 serial transmission of data standard
FDX Full-Duplex RTU Remote Terminal Unit
HDX Half-Duplex PG Industry Standard liquid-tight wiring entry
connector
Hex Hexadecimal Number (0-9, A-F) MB MODBUS
I/O Input/Output
C. Denitions
Figure 1 - BIC-926 Controller Revision Label Location
Table 1 includes a list of denitions used throughout this manual.
Table 1 - Denitions
The MODBUS/BACnet adapter should be mounted to a solid surface. The adapter has two tabs with four mounting holes designed specically
for this purpose.
Part 2 - Installation
Figure 2 - BIC-928 Controller Revision Label Location
WARNING
!
Be sure to disconnect electrical power before opening boiler cabinet or performing
service. Label any wiring removed from the appliance to aid in rewiring. Failure to
do so could result in electrical shock, appliance and/or property damage, serious
personal injury, or death.
This adapter is capable of supporting either the MODBUS or BACnet protocols. The protocol selection is accomplished via dipswitch 10.
MODBUS and BACnet communication systems utilize a master-follower format where connected HTP appliances follow commands from a
building management system or other MODBUS or BACnet master device linked over an RS-485 serial connection.
Part 1 - General Information
refer to Figure 1 and observe the label on the control cover. On BIC-928 products, turn o power to the appliance. Then remove the wire
harnesses from the control. Then remove the control cover and observe the label on the control board. See Figure 2.
3. Shielded twisted pair communication cable.

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CAUTION
Use the mounting template and screws provided with the adapter. Damage to the MODBUS/BACnet 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 RS-485 communication cable, and that the
appliance communication wire must reach the control inside the appliance.
The MODBUS/BACnet 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 input port.
In BIC-926 based appliances, the four pin connector from the adapter must be plugged into the white connector labeled X3 on the
control.
In BIC-928 based appliances, the four pin connector from the adapter must be plugged into the black connector labeled X4 on the
control.
In both cases the adapter end of the four pin cable MUST be plugged into the BLACK connector labeled BIC X3 of the adapter circuit
board!
NOTE: It is not recommended to install the MODBUS/BACnet adapter inside the appliance housing. Doing so may aect appliance operation
or damage the MODBUS/BACnet adapter.
A. BMS Wiring Requirements
RS-485 Communication Bus
• Maximum length: 4000
feet
• Cable specication: 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 3 for an example wiring
diagram.
Figure 3 - Jumper Congurations in a MODBUS / BACnet Network
CAUTION
Damage to MODBUS/BACnet adapter or appliance due to improper installation IS NOT covered by warranty.
B. Jumper Setting
The appliance display handles
most of the MODBUS/BACnet
adapter conguration. There is
one jumper on the MODBUS/
BACnet 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/BACnet adapter is at
the end of the RS-485 bus. Remove
the jumper if the MODBUS/
BACnet adapter is one of many
connections and not at the end of
the bus. See Figures 3 and 4.
Figure 4 - MODBUS Termination Jumper Location (Highlighted in Grey)

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Part 3 - Communication Conguration
A. MODBUS/BACnet Enable
In order to enable either MODBUS or BACnet, push
dipswitch 10 into the ON position to enable BAC,
and the OFF position to enable MODBUS. See the
dipswitch matrix below for a detailed description.
Final Baud Rate Protocol
1 2 3 4 5 6 7 8 9 10
x4 BACNET
OFF OFF OFF OFF OFF OFF OFF OFF x1 MODBUS
Table 2 - Dipswitch Matrix
ENTER MENU CODE
925
LCD Display:
1. On the LCD display press and hold ENTER until you see the screen at the right.
2. Use the RIGHT arrow to select a character, then use the UP and DOWN arrows to select the desired
Parameter 3 Character LED Display Setting LCD Text Display Setting Description
37 0 OFF MODBUS/BACnet “DISABLED” (factory default)
37 1 AUTOMATIC MODBUS/BACnet“AUTO” (enables automatic detection of a PC or Adapter)
37 2 ON MODBUS/BACnet “ON”
Table 3 - MODBUS MODE Settings
Please do not leave the Installer Menu after making this selection. Continue to congure the Address, Baud Rate, and Parity settings.
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 dened 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.
C. BACnet Address
BACnet Device Instance
The unique BACnet Device instance number will consist of three (3) parts:
Base Number: 600000 Family:
BIC926 00000
BIC928 01000
The local address will be set by the MODBUS menu on the BIC. This address is the same as the address on the RS485 bus.
Example: A BIC928 with the RS485 address of 65 will have a device ID of 601065. A BIC926 with the RS485 address of 31 will have a device
ID of 600031.
NOTE: MODBUS must be enabled on the appliance as outlined above for the following parameters to be viewed and changed.
The BACnet address space is comprised of 256 addresses. These are dened as follows:
• Address 255 is a broadcast address. The master can send data to address 0 and all followers will process the data.
• Addresses 0 – 127 are free to be assigned to both Master and Follower BACnet nodes. Each address can be assigned to only one
BACnet device on the bus.
• Addresses 128 – 254 are valid only for Follower nodes.
ADDRESSING SUGGESTIONS*
• Each device must have a unique address.
• 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/BACnet adapter address in the appliance installer menu:
LCD Display:
1. When at Parameter 38, press ENTER, then use UP or DOWN to select the desired address.
2. Press ENTER to store the MODBUS Address.
3. Press the RIGHT button to advance to Parameter 39 – Baud Rate.
character value. RIGHT arrow over to the next character and repeat the selection. Once code 925 or 975 is on the screen (Installer Menu
code depends on the appliance - See appliance Installation Manual for details), press and hold ENTER on the display to enter the Installer
Menu.
3. Once in the Installer Menu, use the RIGHT or LEFT arrow to navigate to Parameter 37-MODBUS MODE. When at Parameter 37, press
ENTER, then use UP or DOWN to select the desired setting from Table 3.
4. Press ENTER to store the MODBUS Conguration. Press the RIGHT button to advance to Parameter 38 - Address.
LED Display:
1. On the LED display, press and hold TEMP and RESET simultaneously. Use the + and - arrows to show 925 on the display, then press and
hold TEMP to enter the installer menu.
2. Once in the Installer Menu, use the TEMP button to navigate to Parameter 37. When at Parameter 37, use + or - to select the desired
setting from Table 3.
3. Press the TEMP button to advance to Parameter 38 - Address.

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D. Baud Rate
The baud rate (communication speed) can be set on the control display to either 9600 or 19200 baud. All HTP appliances, as well as any other
device on the same bus and the MODBUS/BACnet master, must have the same baud rate setting. Select the highest baud rate that oers the
most reliable communication performance over the bus.
Some things that can aect 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.
LCD Display:
1. When at Parameter 39, press ENTER, then use UP or DOWN to select the desired setting from Table 4.
2. Press ENTER to store the Baud Rate.
3. Press the RIGHT button to advance to Parameter 40 – Parity.
LED Display:
1. When at Parameter 39, press TEMP, then use + or - to select the desired setting from Table 4.
2. Press the TEMP button to advance to Parameter 40 – Parity.
Parameter 3 Character LED Display Setting LCD Text Display Setting Description
39 0 9600 BAUD RATE = 9600 (factory default)
39 1 19200 BAUD RATE = 19200
Table 4 - Parameter 39 Settings
The nal (RS-485) baud rate is determined by this setting in
conjunction with dipswitch 9 on the adapter. Table 5 shows all
possible nal baud rate selections.
LED Display:
1. When at Parameter 38, press TEMP, then use + or - to select the desired address.
2. Press the TEMP button to advance to Parameter 39 – Baud Rate.
Control Baud Rate Setting Dipswitch 9 Position Final RS-485 Baud Rate
9600 OFF 9600
19200 OFF 19200
9600 ON 36400 (9600 X 4)
19200 ON 76800 (19200 X 4)
Table 5 - Final Baud Rate Settings
E. Parity and Stop Bits
NOTE: This setting only applies to MODBUS operation. The
BACnet protocol does not utilize parity for communication and
this setting will have no eect.
The parity/stop bits parameter of the MODBUS/BACnet 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 sucient to establish communication with other devices. These selections are
outlined in Table 6.
LCD Display:
1. When at Parameter 40, press ENTER, then use UP or DOWN to select the desired setting from the table below.
2. Press ENTER to store the Parity.
3. Press and Hold the RESET button to store all parameters and exit the Installer Menu.
Parameter 3 Character LED Display Setting LCD Text Display Setting Description
40 0 1 ST No parity 1 stop bit (factory default)
40 1 2 ST No parity 2 stop bits
40 2 E PA Even parity 1 stop bit
40 3 O PA Odd parity 1 stop bit
Table 6 - Parameter 40 Settings
Part 4 - MODBUS Registers and BACnet Objects
A. Primary Data Tables
Table Data Type Read / Write Description
Discrete Inputs Single bit Read only Data can be provided by an I/O system.
Coils Single bit Read / Write Data can be altered by an application program.
Input Registers 16-bit word Read only Data can be provided by an I/O system.
Holding Registers 16-bit word Read / Write Data can be altered by an application program.
Table 7 - Supplementary Information
LED Display:
1. When at Parameter 40, press
TEMP, then use + or - to
select the desired setting
from Table 6.
2. Press and Hold the RESET
button to store all parameters
and exit the Installer Menu.

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NOTE: BOLD ITALICS indicate objects that apply only to appliances equipped with BIC-928 operating systems.
B. Appliance Memory Map
MODBUS Heating Appliance Water Heater BACNET
Address Description Description Object Type Object Instance Unit Resolution
Discrete Inputs Discrete Inputs
00001 En / Room Th1 / Stg 1 N/A BV 0 1 = on, 0 = o 1
00005 Tank thermostat N/A BV 4 1 = on, 0 = o 1
10001 MHRL High temp safety switch / High ue temp
switch BI 0 1 = on, 0 = o 1
10002 Flow switch N/A BI 1 1 = on, 0 = o 1
10003 Gas Press. Switch N/A BI 2 1 = on, 0 = o 1
10005 Air Press Switch N/A BI 4 1 = on, 0 = o 1
10006 Blocked drain Blocked vent pressure switch BI 5 1 = on, 0 = o 1
10007 ARHL High temp safety switch / High ue temp
switch BI 6 1 = on, 0 = o 1
10008 Flame 1 Flame rectication probe BI 7 1 = on, 0 = o 1
10009 Enable / STG1 N/A BI 8 1 = on, 0 = o 1
10010 Tank th N/A BI 9 1 = on, 0 = o 1
10011 STG2 / APS N/A BI 10 1 = on, 0 = o 1
10033 Run-time cont. 1 Run-time cont. 1 BI 32 1 = on, 0 = o 1
10034 Alarm cont. 1
(EXCEPT Versa Hydro) Alarm output BI 33 1 = on, 0 = o 1
10035 CH pump 1 N/A BI 34 1 = on, 0 = o 1
10036 DHW pump 1 N/A BI 35 1 = on, 0 = o 1
10038 Gas valve 1 Gas valve BI 37 1 = on, 0 = o 1
10039 Sys pump N/A BI 38 1 = on, 0 = o 1
10049 Boiler 1 Run
(same as 11118) Run status BI 48 1 = on, 0 = o 1
10050 Boiler 2 Run
(same as 10023) N/A BI 49 1 = on, 0 = o 1
10051 Boiler 3 Run N/A BI 50 1 = on, 0 = o 1
10052 Boiler 4 Run N/A BI 51 1 = on, 0 = o 1
10053 Boiler 5 Run N/A BI 52 1 = on, 0 = o 1
10054 Boiler 6 Run N/A BI 53 1 = on, 0 = o 1
10055 Boiler 7 Run N/A BI 54 1 = on, 0 = o 1
10056 Boiler 8 Run N/A BI 55 1 = on, 0 = o 1
10057 Lockout 1
(same as 10034) Lockout Status BI 56 1 = on, 0 = o 1
10058 Lockout 2
(same as 10042) N/A BI 57 1 = on, 0 = o 1
10059 Lockout 3 N/A BI 58 1 = on, 0 = o 1
10060 Lockout 4 N/A BI 59 1 = on, 0 = o 1
10061 Lockout 5 N/A BI 60 1 = on, 0 = o 1
10062 Lockout 6 N/A BI 61 1 = on, 0 = o 1
10063 Lockout 7 N/A BI 62 1 = on, 0 = o 1
10064 Lockout 8 N/A BI 63 1 = on, 0 = o 1
10065 Alarm relais ecs
(Versa Hydro ONLY) BI 64 1 = on, 0 = o 1
Input Registers Input Registers
30001 Discrete Inputs 1-16 N/A AI 0 N/A 1
30002 Discrete Inputs 17-32 N/A AI 1 N/A 1
30003 Discrete Inputs 33-48 N/A AI 2 N/A 1
30004 *System / Cascade Setp. N/A AI 3 Deg F, O = 32 0.1

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MODBUS Heating Appliance Water Heater BACNET
Address Description Description Object Type Object Instance Unit Resolution
Input Registers Input Registers
30005 System Pump 4 speed N/A AI 4 % 1
30006 Cascade Total Power N/A AI 5 % 1
30007 Cascade Current Power N/A AI 6 % 1
30008 *Outlet Setp. 1 N/A AI 7 Deg F, O = 32 0.1
30009 Outlet Temp. 1 Upper Temp Sensor AI 8 Deg F 0.1
30010 Inlet Temp. 1 Lower Temp Sensor AI 9 Deg F 0.1
30011 Flue Temp. 1 N/A AI 10 Deg F 0.1
30012 Firing Rate 1 Firing Rate 1 AI 11 % 0.1
30013 Boil. 1 Pump speed 5 N/A AI 12 % 1
30014 Boil. 1 Status Code Status Code 1 AI 13 N/A 1
30015 Boil. 1 Blocking Code Blocking Code 1 AI 14 N/A 1
30016 Boil. 1 Lockout Code Lockout Code 1 AI 15 N/A 1
30018 Outlet Temp 2 N/A AI 17 Deg F 0.1
30021 Firing Rate 2 N/A AI 20 % 0.1
30022 Boil. 2 Pump 4 speed N/A AI 21 % 1
30023 Boil. 2 Status Code N/A AI 22 N/A 1
30024 Boil. 2 Blocking Code N/A AI 23 N/A 1
30025 Boil. 2 Lockout Code N/A AI 24 N/A 1
30026 Boiler Outlet 3 N/A AI 25 Deg F 0.1
30027 Boiler 3 Firing Rate N/A AI 26 % 1
30028 Boiler 3 Status N/A AI 27 N/A 1
30029 Boiler 3 Lockout N/A AI 28 N/A 1
30030 Boiler Outlet 4 N/A AI 29 Deg F 0.1
30031 Boiler 4 Firing Rate N/A AI 30 % 1
30032 Boiler 4 Status N/A AI 31 N/A 1
30033 Boiler 4 Lockout N/A AI 32 N/A 1
30034 Boiler Outlet 5 N/A AI 33 Deg F 0.1
30035 Boiler 5 Firing Rate N/A AI 34 % 1
30036 Boiler 5 Status N/A AI 35 N/A 1
30037 Boiler 5 Lockout N/A AI 36 N/A 1
30038 Boiler Outlet 6 N/A AI 37 Deg F 0.1
30039 Boiler 6 Firing Rate N/A AI 38 % 1
30040 Boiler 6 Status N/A AI 39 N/A 1
30041 Boiler 6 Lockout N/A AI 40 N/A 1
30042 Boiler Outlet 7 N/A AI 41 Deg F 0.1
30043 Boiler 7 Firing Rate N/A AI 42 % 1
30044 Boiler 7 Status N/A AI 43 N/A 1
30045 Boiler 7 Lockout N/A AI 44 N/A 1
30046 Boiler Outlet 8 N/A AI 45 Deg F 0.1
30047 Boiler 8 Firing Rate N/A AI 46 % 1
30048 Boiler 8 Status N/A AI 47 N/A 1
30049 Boiler 8 Lockout N/A AI 48 N/A 1
30050 Discrete Inputs 49 - 64 N/A AI 49 N/A 1
30051 NTC 6 temperature N/A AI 50 Deg F 0.1
30052 NTC 7 temperature N/A AI 51 Deg F 0.1
30053 NTC 9 temperature N/A AI 52 Deg F 0.1
30054 Vortex 1 ow N/A AI 53 LPM 0.1
30055 Vortex 1 temp N/A AI 54 Deg F 0.1

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MODBUS Heating Appliance Water Heater BACNET
Address Description Description Object Type Object Instance Unit Resolution
Input Registers Input Registers
30056 Vortex 2 ow N/A AI 55 LPM 0.1
30057 Vortex 2 temp N/A AI 56 Deg F 0.1
30091 Total Faults N/A AI 90 1
30092 Total Last Faults N/A AI 91 1
30093 Run Hours CH AI 92 x5
30094 Run Hours DHW AI 93 x5
30095 Run Hours Cas CH N/A AI 94 x5
30096 Run Hours Cas DHW N/A AI 95 x5
30097 Power Hours AI 96 x5
30099 Start Counter AI 98 1
30100 Start Counter AI 99 1
Holding Registers
40001 Conguration Conguration AV 0 See
Conguration
Bits Section
1
40002 Coils Coils AV 1 1
40003 0-10 volt / rate / setp 0-10 volt / rate / set AV 2 V 0.1
40004 DHW setpoint DHW set AV 3 Deg F 0.1
40005 DHW temperatur DHW temp AV 4 Deg F 0.1
40006 Outdoor temp. Outdoor Sensor AV 5 Deg F 0.1
40007 Sys supply temp. N/A AV 6 Deg F 0.1
40008 Sys rtn temp. N/A AV 7 Deg F 0.1
40009 I4 for direct N/A AV 8 Deg F 0.1
40010 CH post purge N/A AV 9 Seconds 1
40011 DHW post purge N/A AV 10 Seconds 1
40012 Pump 4 Speed N/A AV 11 % 0.1
40014 Extra out ECS N/A AV 13 % 0.1
Table 8 - MODBUS and BACnet Memory Map - *Only Valid Valves During Heating Cycle
Address 40001/AV0 contains conguration bits sent from the BMS to the appliance. These bits tell the appliance to use its own internal inputs,
or inputs from the BMS. When a bit is set to 1, the appliance will ignore the corresponding value contained internally and expect the BMS to
write that value into the holding registers. The conguration bits are as follows:
C. Conguration Bits
Holding Register 40001 / AV0 Decimal Value HEX Value Selected Signal (Register) to Write to 0 = Taken from Control
1 = Taken from MODBUS
B0 (LSB) 1 01 Boiler enable (40002 / AV1) 0/1
B1 2 02 Tank enable (40002 / AV1) 0/1
B2 4 04 Rate command / 0-10V input / setpoint command
(40003 / AV2) 0/1
B3 8 08 DHW setpoint (40004 / AV3)* 0/1
Holding Register 40001 / AV0 Decimal Value HEX Value Selected Signal (Register) to Write to 0 = Taken from Control
1 = Taken from MODBUS
B4 16 10 DHW temperature (40005 / AV4) 0/1
B5 32 20 Outdoor temperature (40006 / AV5) 0/1
B6 64 40 System supply temperature (40007 / AV6) 0/1
B7 128 80 System return temperature (40008 / AV7) 0/1
B8 256 100 I4 oset (40009 / AV8) 0/1
B9 512 200 CH post purge (40010 / AV9) 0/1
B10 1024 400 DHW post purge (40011 / AV10) 0/1
B11 2048 800 Pump 4 speed (40012 / AV11) 0/1
B12 4096 1000 Pump 5 speed (40013 / AV12) 0/1
B13 (MSB) 8192 2000 Extra 0-10V output (40014 / AV13) 0/1

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Table 9 - MODBUS Holding Registers
*The appliance will not respond to the internal DHW limit while the Tank Temperature AND Tank Enable is being written from
MODBUS/BACnet!
Part 5 - Appliance Operation
A. Appliance Operation with MODBUS and BACnet Communications
The appliance is equipped with a communication timer. Timeout is set for four minutes. The purpose of the timer is to ensure proper
temperature data is communicated to the appliance in a timely manner.
Additionally, the communication timer will provide fail safe operation should communication be lost. This timer will cause the appliance to
revert back to internal appliance controls should the communication be interrupted longer than the timer. The timer resets every time a write
command is received with updated temperatures or commands.
The master should update temperature registers at least once per minute, but no more than once per second.
Monitoring Only
Any appliance can be equipped with the MODBUS or BAC/net communication accessory and then be set up to operate with its own internal
controls. The master can then poll the MODBUS or BAC/net accessory for the read only variables. Refer to the following examples for
conguring the writable Holding Registers.
Holding Register 40002 / AV1 Selected Signal (Register) to Write to)
Coil 01 b0 1 01 Room thermostat
Coil 05 b4 16 10 Tank thermostat
B. Example #1 - Enable / Disable CH and DHW Demand
In this conguration, the appliance is controlled by setting the setpoints locally on the appliance and providing an enable signal through
MODBUS or BAC/net communications.
All sensors and limiting devices (excluding the thermostat enable and tank thermostat enable signals, which will be sent to the appliance)
should be hardwired to the proper terminals in the appliance. The holding registers need to be set as follows:
Holding Registers Denition Decimal
Value HEX Value Action
40001 / AV0 Conguration 3 0011 Set conguration to read 40002
40002 / AV1 Coils 1 0001 Enables CH Demand (00 00 disables demand) (boilers only)
40002 / AV1 Coils 16 0010 Enables DHW demand on appliance (00 00 disables demand)
40002 / AV1 Coils 17 0011 Enables both CH and DHW demand. DHW demand will have priority.
Table 10 - Example #1
Holding Registers Denition Decimal
Value HEX Value Action
40001 / AV0 Conguration 8 0010 Set conguration to read 40004/AV3
40004 / AV3 Coils Setpoint Setpoint Directly writes setpoint to water heater
C. Example #2 - Sending DHW Setpoint Via Direct Write Method
Table 12 - Example #2
*The appliance will not respond to the internal DHW limit while the Tank Setpoint is being written from MODBUS/BACnet!
D. Example #3 - Sending Setpoint or Firing Rate from BMS
In this conguration, the appliance setpoint is indirectly controlled by sending a 0 to 10v signal to it. All sensors and limiting devices (excluding
1. Sending Desired Setpoint from BMS to Appliance Via Simulated 0-10V Method
Appliance Parameter I16 Parameter I17
Phoenix, Munchkin, MODCON rev2 and earlier 2 0
Elite, Elite Premier, EnduroTi 0-10 Volt Temperature
Table 11 - Send Desired Setpoint from BMS to Appliance
To send a desired CH setpoint on an appliance, or DHW setpoint on a water heater via 40003/AV2, the value (which equates to voltage applied)
must be determined through linear interpolation of programmable parameters on the BMS setup menu.
• Appliance temperature setpoint at low analog input = MIN BOILER TEMP (I12) in the 925 Installer Menu
• Appliance temperature setpoint at high analog input = CENTRAL HEAT in the 600 User Menu or PHOENIX in the User Menu
These variables set the temperature values corresponding to the minimum and maximum voltage settings of the 0 – 10 volt signal. The
defaults are as follows:
the 0 – 10 Vdc signal, which will be sent to the MODBUS/BACnet
adapter) should be hardwired to the correct locations on the
appliance.
For this command to function, congure the appliance
according to the corresponding row in the table to the right.

lp-548 Rev. 000 Rel. 004 Date 1.11.19
10
For example: Send a setpoint of 110oF. The formula to use for the interpolation is:
Voltage to be applied = (Desired setpoint – BMS temp at low analog input) (High voltage – low voltage) + Low voltage
(BMS temp at high analog input – BMS temp at low analog input)
From the default values:
Desired setpoint = 110
BMS temp at low analog input = 68
BMS temp at high analog input = 180
High voltage = 10
Low voltage = 1.6
[(110 - 68)(10-1.6)/(180 - 68)] + 1.6 = 4.75 volts
(4.75/10) x 100 = 47.5 48 = 30 Hexadecimal
A value of [00] [30] in hexadecimal would be written to holding register 40003/AV2 to issue a command for a 110oF setpoint.
NOTE: If your particular BMS supports DECIMAL inputs, then the desired voltage level can be sent directly. In the above example, you would
send 48 (4.8v) to 40003/AV2.
The holding registers need to be set as follows:
Holding Registers Denition Decimal Value HEX Value Action
40001 / AV0 Conguration 4 04 Set conguration to read 40002
40003 / AV2 Setpoint 0-100 00-64 Enables CH Demand (00 00 disables demand)
Table 14 - Setting Holding Registers for Setpoint
Register 40003/AV2 needs to receive the
setpoint command as follows: Acceptable
range is 0 to 100. Value needs to be greater
than 15 for the appliance to re.
When the command is 16, the appliance will
run with the setpoint controlled by the 925
menu parameter I12 (MIN BOILER TEMP).
When the command is 100 the appliance
will run with the setpoint controlled by the
600 menu parameter CENTRAL HEAT on
appliances or the PHOENIX setting in the
water heater user menu.
If the command value is anywhere between
16 and 100, the appliance will run at a setpoint
proportional to the command sent between
minimum and maximum setpoints.
NOTE: To ensure proper operation, resend
the conguration bits to holding register
40001 / AV0 prior to issuing a command.
1.5V
10V
Figure 5 - Setpoint Curve
In this conguration, the appliance is controlled by setting the modulation from 0 – 100%. Rate command will be 0 – 100% of the modulation
range. All sensors and limiting devices (excluding the 0 – 10 Vdc signal, which will be sent to the MODBUS/BACnet adapter) should be
hardwired to the correct locations on the appliance.
For this command to function, congure the appliance according to the corresponding row in the following table.
2. Send Firing Rate Command from BMS to Appliance
Appliance Parameter I16 Parameter I17
Phoenix, Munchkin, MODCON rev2 and earlier 2 2
Elite, Elite Premier, EnduroTi 0-10 Volt Fan Speed
Table 15 - Send Firing Rate from BMS to Appliance
The holding registers need to be set as follows:
Holding Registers Denition Decimal Value HEX Value Action
40001 / AV0 Conguration 4 04 Set conguration to read 40003
40003 / AV2 Rate Command 0-100 00-64 Sets Modulation %
Table 16 - Setting Holding Registers for Firing Rate
Parameter Default Values Default
Deg C Deg F Voltages
Appliance temperature setpoint at low analog input 21 68 1.6
Appliance temperature setpoint at high analog input 82 180 10
Table 13 - 0-10 Volt Temperature Values for Setpoint