Installation guide

Glossary
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890USE17100 September 2003
output polarity An output channel’s polarity determines when the output module turns its field
actuator on and when it turns the actuator off. If the polarity is normal, an output
channel will turn its actuator on when the master controller sends it a 1. If the polarity
is reverse, an output channel will turn its actuator on when the master controller
sends it a 0.
output response
time
The time it takes for an output module to take an output signal from the island bus
and send it to its field actuator.
parameterize To supply the required value for an attribute of a device at run-time.
PDM power distribution module. A module that distributes either AC or DC field power to
a cluster of I/O modules directly to its right on the island bus. A PDM delivers field
power separately to the input modules and the output modules. It is important that
all the I/O clustered directly to the right of a PDM be in the same voltage group—
either 24 VDC, 115 VAC, or 230 VAC.
PDO process data object. In CAN-based networks, PDOs are transmitted as unconfirmed
broadcast messages or sent from a producer device to a consumer device. The
transmit PDO from the producer device has a specific identifier that corresponds to
the receive PDO of the consumer devices.
PE protective earth. A return line across the bus for fault currents generated at a sensor
or actuator device in the control system.
peer-to-peer
communications
In peer-to-peer communications, there is no master/slave or client/server
relationship. Messages are exchanged between entities of comparable or
equivalent levels of functionality, without having to go through a third party (like a
master device).
PLC programmable logic controller. The PLC is the brain of an industrial manufacturing
process. It automates a process as opposed to relay control systems. PLCs are
computers suited to survive the harsh conditions of the industrial environment.
P