Would it be possible to extend timing diagrams for a ladder logic?
* hiding grid or specifying grid color as #hidden
* hiding ticks labels for robust and analog participants
* adjusting or specifying label positions for robust participants (vertical-align: middle)
* Specifying line types of messages
* Optionally specifying the vertical position of end points for analog participants
* Manually specifying time range such as "range time-axis between 0.75 and 3.75" (not shown in the desired diagram below)
Diagram with plantuml.1.2020.14.jar:

Desired diagram:

Possible commands:
@startuml
mode compact
hide time-axis
hide grid
robust "TLR" as TLR
analog "TLR-a (NO)" between 0 and 1 as TLRa
analog "TLR-b (NC)" between 0 and 1 as TLRb
TLR ticks none
TLRa ticks none
TLRa is 36 pixels height
TLRb ticks none
TLRb is 36 pixels height
TLRb is 1.0
@TLR
0 is 0
1 is 1
@1 <-> @2: delay
TLR@2 .[#gray]. TLRb@2,0.0
3 is 0
TLR .[#gray]. TLRb
@TLRa
0 is 0
2 is 0
2.4 is 1
3 is 1
3.2 is 0
@TLRb
2 is 1
2.2 is 0
3 is 0
3.4 is 1
@enduml