A-B 1747-ASB Module Rockwell SLC Combined Module

Heat/Cool Minimum On-times

Words 6 and 8 for channel 1

These values determine the minimum cycle time after which loop

TPO bits will turn ON. They are used to allow contactors time to close

or pull in. If the contactor is energized for less than this value, the

contactor will not close, but the attempt will count as a cycle.

For example, suppose you set the TPO period for 10 seconds and the

minimum ON time to 1 second. Then if the module calculates a CV%

of 10% or less, the TPO bit for that zone will not turn ON.

Heat/Cool TPO Period

Words 7 and 9 for Channel 1

When CV loop output is time–proportioned (TPO), use this value to

set the interval between successive turn–ONs. For less than a 100%

output level, the output goes OFF for the balance of the interval.

PV Rate and Associated Alarm

Word 10 and Alarm Bit I:e.4/05 for Channel 1

The PV Rate is a setpoint with an associated alarm that indicates when

the temperature is rising too rapidly. If the zone’s PV has risen more

than this setpoint in one second (in auto mode), the module sets the

PV rate alarm bit (I:e.4/05, loop 1). The module only reports this

alarm - no action is taken.

Data Highway Plus (DH+) channel offers:

• communication rates of 57.6 Kbaud, 115.2 Kbaud, and 230.4 Kbaud.

• maximum network length of 3048 m (10,000 ft) at 57.6 Kbaud

• Belden 9463 (blue hose) cable connection between nodes (daisy chain connection).

• built-in isolation.

DH-485 channel offers:

• configurable isolation via the 1747-AIC or 1761-NET-AIC interfaces.

• maximum network length of 1219 m (4000 ft).

• RS-485 electrical specifications.

• Belden 9842 or Belden 3106A cable connection between nodes (daisy-chain connection).

Processor Communication Options

The SLC 500 processors support several communication options. 

The following sections describe the available physical connections and protocol options used by the SLC 500 processors.

Physical Connection Options

Ethernet (10/100Base-T) channel offers:

• 10/100 Mbps communication rate.

• ISO/IEC 8802-3STD 802.3 (RJ45) connector for 10/100Base-T media.

• TCP/IP communication protocol.

• built-in isolation.

Barrel Control

Select barrel control for multiple–zone applications in which there is

thermal conduction between the zones. Injection molding and

extrusion are good example applications because they use multiple

heater bands (zones) mounted on one thermal conductor (the metal

barrel). The barrel conducts heat between different zones. If you

select barrel control, also select between inner and outer zones (word

1, bit 13 for channel 1). A barrel loop is autotuned as the temperature

rises from a cold start to a temperature setpoint during startup.