Modulex Controller Operation
8
Figure 1-11. Location of BCM Address Selection Switch SW1
1.7.2 MONITORING AND CONFIGURATION
ONLY
For monitoring and configuration only, set the 3-position switch
to position II when the E8 is controlling the boiler. The boiler
operation can be monitored via the Modbus terminals.
1.7.3 MODBUS DIRERCT DRIVE CONTROL
AND MONITORING
The BCM’s modulation output can be directly driven by writing
to its Direct Drive register (Standard Holding Register). It
will ramp up the boiler based on the settings in the Standard
Holding Register or Setting Register 3000 to 3051. The default
maximum setpoint temperature limit is 85°C as shown in
register 3015. This value should not be increased, if possible.
The default timeout interval is 30 seconds as shown in register
3011. To prevent communication dropouts, write the direct
drive modulation value at least 3 times within the
communication timeout interval.
1.7.4 MODBUS REMOTE SETPOINT
CONTROL AND MONITORING
To send a setpoint temperature to the BCM and have it control
the boiler based on its internal settings, 3 registers need to be
adjusted:
1. the desired setpoint should be written to the Requested
Setpoint (Address 1004)in the Standard holding Registers
or Control Registers. This value should be written at least
3 times within the Communication Timeout time (Address
3011).
2. The Heat Request Command (Control Register Address
1021) should be set to 0xEE (238) to request heat.
3. If the modulation level should be allowed to go above
50%, adjust the Maximum Modulation Level setting (Ad
dress 1017).
NOTE
If power is lost, all Control Register settings re-
turn to their default values. Be sure to read them
regularly and refresh if necessary. The changes
to the Settings Registers are stored during
power-down.
1.7.5 EMS OR BAS SET-UP AS MASTER TO
BCM CONTROLLER SLAVES
Ref
u
er to the set-up instructions in the man facturer’s equip-
ment manual for the Energy Management System (EMS) or
Building Automation System (BAS) being used as the control-
ling Master.
1.7
MODBUS SOFTWARE SET-UP
The following paragraphs provide the information and proce-
dures necessary to configure the Boiler Communications
Modules (BCMs) to operate on a Modbus Network.
NOTE
The following paragraphs assume that between
1 and 9 Modulex Boilers are being controlled on
the Modbus Network.
7.7.1 BCM Set-Up for Modbus Operation
The BCM Controller can be set up for the following types of
Modbus operating modes:
• Monitoring and Configuration Only
• Modbus Direct Drive Control and Monitoring
• Modbus Remote Setpoint Control and Monitoring
In order for the BCM Controller to be recognized by the Mod-
bus Master, a valid address must be set at each BCM on the
Modbus Network. Address selection on each BCM is accom-
plished by setting rotary DIP switch SW1. This switch is loca-
ted in the lower right portion of each BCM as shown in Figure
1-11.
As Figure 1-11 shows, SW1 is a 10-position switch labeled 0
– 9. SW1 is set to the desired position using a small flat-tip
screwdriver. Figure 1-11 shows SW1 set to address 0 (zero)
which disables the BCM on the Modbus Network. Only Mod-
bus addresses 1 through 9 will be recognized by the Modbus
Master. SW1 must be set to a different position for each Modu-
lex Boiler being controlled on the Modbus Network.
Once the desired address has been set on each BCM, the
Modulex Boiler is configured for Modbus Network control by
the controlling Master EMS/BAS. In order for the BCM to act as
the Back-Up Controller if the Modbus Master signal is lost, the
ENABLE/DISABLE switch must be set to ENABLE (1).
See Appendix B for Modbus points for the BCM.
