Diagnostics Message Frame; Message Frame Structure; Contents Of The Message Frame - Siemens 6ES7 972-4AA02-0XA0 User Manual

User´s Guide Power Rail Booster

7.2 Diagnostics Message Frame

The PRB's SF contact can be evaluated in two different ways.
•
DIP switch DIP-6 "Off":
• DIP switch DIP-6 "On":
The system transfers the message frame on an event-driven basis. A new transfer
always takes place when the status of one or more bits in the message frame
changes, e.g. in the case of a coming and going error. If the status of one or more bits
changes while a message frame is being sent or in the break between two message
frames (approximately 1 second), it is transferred in the next status message frame. If
the status changes more than once in this time – such that the status bits of the first
message frame are valid again at the end of the message frame break – the system
does not send a new status message frame, since the current status corresponds to
that of the last message frame! If there is a change, the system carries out
transmission with the current status bits.
7.2.1

Message Frame Structure

The transferred character is one byte comprising eight bits of user data. For
synchronization, the system additionally transfers one start bit, one zero bit and one
stop bit. Data backup is carried out with one parity bit. The system functions with
even parity.
Fig. 29: Structure of the Diagnostics Message Frame
7.2.2

Contents of the Message Frame

The following table lists the data bits and explains their meanings.
Bit Name
Start bit Start
0 Bit Zero bit
7 (MSB) SF
6 KS
5 Limit Temp
4 Over Temp
3 <Reserve>
2 <Reserve>
1 Bd-Lost
0 (LSB) <Reserve>
Parity Parity
Stop bit Stop
Fig. 30: Contents of the Diagnostics Message Frame
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The PRB's SF contact can be evaluated in two
different ways, as described in chapter 7.1
The system issues a bit-serial diagnostics message
frame via the SF contact to terminal 14. Evaluation
is carried out by means of a standard function block
for S7 as described in chapter 9.1.3
Meaning
Short circuit on Power Rail
Sequence bit logical 0
0=OK 1=Group error
0=OK 1=Short circuit on Power Rail
0=OK 1=Limit temperature reached
0=OK 1=Overtemperature reached
<Reserve>
<Reserve>
0=OK 1=Baud rate lost
<Reserve>
Parity bit (even)
Stop bit logical 1
6ES7 972-4AA02-0XA0
Version 12/2005
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