ProSoft Technology PTQ-PDPMV1 - Manual (Page 194)

Hot Standby Support PTQ-PDPMV1 ♦ Quantum Platform
User Manual PROFIBUS DP Master Network Interface Module for Quantum
Page 194 of 306 ProSoft Technology, Inc.
August 12, 2014
Standby to Offline (5)
The time it takes to switch to offline is not critical since the transition would not
influence the operation of the counter part, which will carry on working as a
stand-alone Master.
Note: For additional information and restrictions with Quantum processor behavior, refer to the
Unity Pro HSBY User Guide.
7.2.6 HSBY State vs. Master Operation Mode
The matrix below indicates how the Master module would behave on a
PROFIBUS network for all possible combinations of Master operation mode
(OFFLINE, STOP, CLEAR, OPERATE) and "HSBY state" (NOT CONNECTED,
PASSIVE, ACTIVE).
HSBY State vs. Operation Mode
NOT CONNECTED PASSIVE ACTIVE
OFFLINE No network traffic. No network traffic.
STOP Ping requests are issued.
Slave communication takes place Ping requests are responded to.
No slave communication takes place
CLEAR The remote (passive) Master
cannot attain any of these
operation modes.
The application can, however,
instruct the Master to attain one of
these modes after a switchover.
Ping requests are responded to.
Slave communication takes place; only
input data is read.
OPERATE Ping requests are responded to.
Slave communication takes place;
both input- and output data is
exchanged.
7.2.7 Ping Message
The remote (passive) Master would cyclically send ping messages to the local
(active) Master, which in turn would respond to the message.
If the local (active) Master stops receiving ping requests (ping.req in figures
below), it would assume that something is wrong with the counterpart or the field
bus link.
If the remote (passive) Master does not get any response (ping.res in figures
below) to its ping requests it would assume that something is wrong with the
counterpart or the field bus link. In both mentioned cases, the erroneous situation
would be signaled to the application by clearing (0) the COM-bit in the "HSBY
Local Status" register.
The time between ping requests (TP) is bus cycle-dependent. One request is
sent every time the remote (passive) Master is in possession of the token. If
there is no response from the counterpart the ping message would be resent x
times, where x is equal to bus parameter max_retry_limit, before the COM-bit is
cleared. The time the remote (passive) Master waits for a response until it re-
sends the message (TSL) is defined by bus parameter SlotTime.