2
Sensemaking in Safety Critical and Complex Situations
Sensemaking in Safety Critical and Complex Situations
FIGURE 1.1 Pneumatic controller.
FIRST, COMPUTER INTERFACES WERE MERE
COPIES OF THE HARDWARE SOLUTIONS
Technology progressed, and instrumentation became a microprocessor with new
capabilities and transmission over greater distances. They were eventually ending up
connected to a computer through input and output cards. Signals became a mixture
of analogue and digital. The visual display unit ( VDU) became the host of the instrumentation displays, often copied from their pneumatic or electronic representation.
The pneumatic controls became obsolete and were replaced by individual electronic controls but in the same configuration as the pneumatic controls on a metal
panel. This solution had many limitations due to space availability and transmission
distance for the signal, which often was still pneumatic (F igure 1.2).
A “c urrent to pressure” transducer ( I/ P) converts an analogue signal to a proportional linear pneumatic output. The I/ P converter provides a reliable means of
converting an electrical signal into pneumatic pressure in many control systems. The
“ pressure to current” converters ( P/ I) converts a pneumatic signal to a proportional
electrical output.
In the past, the HMI design of hardwired panels focused on optimizing the controls based on process adjustments to allow the operator to stand at one spot on
the board and make moves to control the process. As computerized control became
available, the very first version provided a direct copy of these controls with optimum
grouping, as described below (F igure 1.3).
NO HUMAN FACTORS OR ERGONOMICS WERE
CONSIDERATIONS IN THE DESIGN
As the VDU evolved, it initially emulated the panel instrument displays. However,
this became challenging as hundreds of pages of group displays (w ith eight single
equivalent controllers) became available as more instrumentation was added to
the process plants. There is a need to access relevant controllers based on alarm
Sensemaking in Safety Critical and Complex Situations
Sensemaking in Safety Critical and Complex Situations
FIGURE 1.1 Pneumatic controller.
FIRST, COMPUTER INTERFACES WERE MERE
COPIES OF THE HARDWARE SOLUTIONS
Technology progressed, and instrumentation became a microprocessor with new
capabilities and transmission over greater distances. They were eventually ending up
connected to a computer through input and output cards. Signals became a mixture
of analogue and digital. The visual display unit ( VDU) became the host of the instrumentation displays, often copied from their pneumatic or electronic representation.
The pneumatic controls became obsolete and were replaced by individual electronic controls but in the same configuration as the pneumatic controls on a metal
panel. This solution had many limitations due to space availability and transmission
distance for the signal, which often was still pneumatic (F igure 1.2).
A “c urrent to pressure” transducer ( I/ P) converts an analogue signal to a proportional linear pneumatic output. The I/ P converter provides a reliable means of
converting an electrical signal into pneumatic pressure in many control systems. The
“ pressure to current” converters ( P/ I) converts a pneumatic signal to a proportional
electrical output.
In the past, the HMI design of hardwired panels focused on optimizing the controls based on process adjustments to allow the operator to stand at one spot on
the board and make moves to control the process. As computerized control became
available, the very first version provided a direct copy of these controls with optimum
grouping, as described below (F igure 1.3).
NO HUMAN FACTORS OR ERGONOMICS WERE
CONSIDERATIONS IN THE DESIGN
As the VDU evolved, it initially emulated the panel instrument displays. However,
this became challenging as hundreds of pages of group displays (w ith eight single
equivalent controllers) became available as more instrumentation was added to
the process plants. There is a need to access relevant controllers based on alarm