Chapter 6. COMMREQ/Data_Init_Comm Programming
GFK-2892F
March 2019
65
COMMREQ #4: Read Diagnostics Command
Use this command to request diagnostic information from a Genius device or a bus interface module.
Diagnostics can be requested from any Genius device, even those configured not to issue Report Fault
messages. The diagnostic data returned by a block will indicate faults that have occurred since power-up or
since the last Clear Faults datagram. Current diagnostic state can be found by issuing a Clear Faults command
to the circuit(s) or channel(s) to clear the fault history, then issuing a Read Diagnostics command.
This command causes the Genius Gateway to send a Read Diagnostics datagram to the specified device. When
the device receives this datagram, it returns a Read Diagnostics Reply datagram. I/O blocks return data in
message segments of up to 16 bytes per bus scan. The content of the Read Diagnostics Reply message
depends on the device being queried. The first word of the reply will contain the length of the data that follows.
Data is packed two bytes per word. Message formats are shown in the
Genius I/O System and Communications
User’s Manual
,
GEK-90486-1. When all the data has been received, the Gateway transfers it to the PNC, which
then transfers it to the CPU.
Command Block for the Read Diagnostics Command
Address
Command Length
7
A1
No Wait
0
A2
Status Block memory type
70 (%I), 72 (%Q), 8 (%R), 10 (%AI), 12 (%AQ) or 196 (%W)
A3
Status Block offset
Beginning address for the COMMREQ Status Block.
A4
Idle timeout value
0
A5
Max. communications time
0
A6
Command number
4
A7
PROFINET Device number
1-255: The device number of the targeted GCG Genius Gateway.
A8
Genius Device Number
1-29: the SBA of the targeted Genius Device.
A9
Maximum data memory
length. May represent either
bits or words (depends on
the memory type selected
below).
This entry tells the CPU how much memory is being allocated to store the
diagnostic data returned by the Genius device. The number of bits or
words needed depends on the number of circuits on the block and the
block type:
10 words (160 bits): Discrete blocks, 8-ckt.
18 words (288 bits): Discrete blocks, 16-ckt.
34 words (544 bits): Discrete blocks, 32-ckt.
8 words (128 bits): Analog, 4-in/2-out blocks.
8 words (128 bits): RTD Input blocks.
8 words (128 bits): Thermocouple Input blocks.
6 words (96 bits): High-Speed Counter block.
If the length of data returned by the device exceeds the length specified
here, the GCG writes as much data as possible to the PLC CPU Memory
and returns a data error to the COMMREQ Status Block. The GCG will not
write past the computed end-point.
A10
Deposit Memory type
Enter the code representing the CPU Memory Type where the GCG will
deposit the data obtained from the target Genius Device. Use the same
codes as in 2.
A11
A12
Memory offset
bytes 1, 2
bytes 3, 4
Starting address within the Deposit Memory type.
(Byte 4 is MSB, Byte 1 is LSB)
