43
Setting: HTCBUS or MODBUS ASCII (V3.11+) or MODBUS RTU (V3.11+)
Procedure: Select the HTCBUS™ protocol when communicating with existing Tyco Thermal Con-
trols Heat Trace Control products, including the Model 780/GCC-9000 Group Communications
Controller.
If you are communicating directly with the controller using a different device, select the
MODBUS
protocol. For a detailed description of the controller’s
MODBUS mapping, please refer to the sep-
arate DigiTrace 920 Series Heat Trace Controller—Modbus Protocol Interface Mapping docu-
ment (Tyco Thermal Controls reference H57366 ).
3.9.2 HTCBUS™ ADDRESS
Purpose: Defines the communications address to be used by the controller when using the
HTC-
BUS™
protocol to communicate with a Model 780/GCC-9000. When in the Point A configuration
menu, this sets the Point A
HTCBUS™ ADDRESS; when in the Point B configuration menu, this
sets the Point B
HTCBUS™ ADDRESS. Either may be set independently of the other.
Range: 1 to 16,777,215
Procedure: Set the communications address as desired. This must be an address unique to the
entire communications network to avoid messaging conflicts. The
HTCBUS™ protocol must be
selected in order to set the
HTCBUS™ ADDRESS.
Note: A unique HTCBUS™ communications address is always assigned by Tyco Thermal Controls
and identified by the label on the front of the 920 control module (see Figure 3.1). Use the preas-
signed address whenever possible to minimize the chances of an address being duplicated in the
user’s system.
3.9.3 MODBUS ADDRESS (V3.11 AND UP)
Purpose: The
MODBUS™ ADDRESS, along with the MODBUS™ SUB ADDRESS, defines the commu-
nications address to be used by the controller when using either
MODBUS™ protocol to commu-
nicate with a
MODBUS™ compatible device. When in the Point A configuration menu, this sets the
Point A
MODBUS™ ADDRESS; when in the Point B configuration menu, this sets the Point B MOD-
BUS™ ADDRESS
. Either may be set independently of the other.
Range: 1 to 247
Procedure: Set the communications address as desired. Together with the
MODBUS™ SUB
ADDRESS
, this combination must be unique to the entire communications network to avoid mes-
saging conflicts. Either
MODBUS™ protocol must be selected in order to set the MODBUS™
ADDRESS
.
3.9.4 MODBUS SUB ADDRESS (V3.11 AND UP)
Purpose: The
MODBUS™ SUB ADDRESS, along with the MODBUS™ ADDRESS, defines the commu-
nications address to be used by the controller when using either
MODBUS™ protocol to commu-
nicate with a
MODBUS™ compatible device. When in the Point A configuration menu, this sets the
Point A
MODBUS™ SUB ADDRESS; when in the Point B configuration menu, this sets the Point B
MODBUS™ SUB ADDRESS. Either may be set independently of the other.
Range: 0 to 31
Procedure: Set the communications sub address as desired. Together with the MODBUS™
ADDRESS
, this combination must be unique to the entire communications network to avoid mes-
saging conflicts. Either
MODBUS™ protocol must be selected in order to set the MODBUS™ SUB
ADDRESS
.
Note: Since a 920 HTC does not use all 65,535 data addresses available for each MODBUS™
ADDRESS
, this data address range is subdivided to allow up to 32 HTCs to share the same MOD-
BUS™ ADDRESS
. This increases the number of HTCs allowed on a single MODBUS™ port from 247
to 7,904 (=247 x 32). This requires that any
HTC sharing the same MODBUS™ ADDRESS as
another
HTC must have its own unique MODBUS™ SUB ADDRESS.
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