T3151 Real-Time Clock Communications Modules ICS TRIPLEX

T3151 Real-Time Clock Communications Modules ICS TRIPLEX

T3151 Real-Time Clock Communications Modules ICS TRIPLEX

Real-Time Clock Communications Modules (T3151)
2 Industrial Control Services
Each real-time clock communications module has a Z80 microprocessor, a PROM containing all of the module’s executable
software, static RAM containing program variables, the realtime clock, shared RAM for transferring information between
the processor modules and the communications module’s
microprocessor, and a dual-channel UART with RS-232 serial
port interfaces. Both the clock and the static RAM are
battery-backed. If the system is powered down the battery
continues to keep the clock running. The microprocessor
reads the time, checks it for consistency, and then transfers it
to the shared RAM where it can be read by the processor
modules.
T3151 Each communications module receives power from all three of
the processor modules. A power-sharing circuit in each of the
communications modules receives the power from the three
processor modules and combines it through a diode OR powersharing circuit. This ensures that if one processor module’s
power supply fails, the communications module will continue
to operate by drawing power from the two remaining power
supplies, and the system’s communications functions are
maintained.
The Dual UART (universal asynchronous receiver/transmitter) buffers incoming and outgoing communications
characters. The triplicated processor modules interrupt once
every millisecond to read characters from or write characters
to the communications module.

Communications Module.
T3151 When the processor modules read characters from the
communications module, the communications module sends
characters through triplicated bus drivers to the processor
Safetybus. The processor modules vote this triplicated data
and perform communications processing. When the processor
modules write data to the communications module, the
triplicated data is voted by the communications modules and
sent to the dual UART where it is then transmitted out the
associated port.
The communications modules’ two serial ports operate
independently and can both be configured differently to
support a wide variety of functions including Regent R2