ProSoft Technology PTQ-PDPMV1 - Manual (Page 206)

Hot Standby Support PTQ-PDPMV1 ♦ Quantum Platform
User Manual PROFIBUS DP Master Network Interface Module for Quantum
Page 206 of 306 ProSoft Technology, Inc.
August 12, 2014
PLC HSBY Command Register
The following illustration identifies the operating options provided by the
Command Register (%SW60). The Command Register defines the operation of
the Hot Standby application. That means both the Primary and Standby.
Therefore the Command Register is transferred to the Standby PLC each scan.
As a result, any changes made to the Command Register on the Standby PLC
will have no effect since the value transfer from the Primary side will overwrite it.
%SW60 Hot Standby Command Register
%SW60.0: This bit, if set to 1, allows the Command Register RUN status of the
PLC to be set through the LCD Keypad.
Warning: If the keypad override is enabled while the Hot Standby system is running, the Primary
PLC will immediately read bits 14 and 15 to determine its own state and the state of the Standby. If
both bits are set to 0, a switchover will occur and the former Primary will go offline. The new
Primary will continue to operate.
%SW60.1: Setting this bit = 1 will put PLC A in RUN mode. Setting the bit = 0 will
put PLC A in OFFLINE mode. This bit takes effect only if bit 16 is set = 1.
%SW60.2: Setting this bit = 1 will put PLC B in RUN mode. Setting the bit = 0 will
put PLC B in OFFLINE mode. This bit takes effect only if bit 16 is set = 1.