Retrieve Detailed Channel Status (2002) - GE RX3i User Manual

Chapter 7. Programming SRTP Channel Commands

Retrieve Detailed Channel Status (2002)

The Retrieve Detailed Channel Status command requests that the current Detailed Channel Status words are
returned for a channel. The Detailed Channel Status words contain an active/inactive channel indicator and the
last channel error codes seen. These two words of detailed status supplement the information available in the
COMMREQ Status word and the Channel Status bits. The command has no effect on the value of the Channel
Status bits.
The Detailed Channel Status words are updated every time the status of the channel changes. If the channel is
operating with a fast repetition period, the status words may change faster than the ladder executes the
COMMREQ to retrieve them. If that happens, some status values could be missed by the application program.
Example Command Block
Retrieve detailed channel status for Channel 5. Store the Detailed Channel Status words to Registers %R100–
%R101. Return the COMMREQ status word to %R10.
Word 1
Word 2
Word 3
The term local Word 4
PLC is used here
Word 5
to identify the
Word 6
client PLC—the
Word 7
PLC that initiates
Word 8
the
Word 9
communications
Word 10
request.
(Word 7) Channel Command Number: Requests that Detailed Channel Status words be returned. The Detailed
Channel Status words are written to the location specified in Words 9 and 10. The COMMREQ status word
indicates successful completion of the command. If the specified channel is not currently in use, the latest
status is returned.
(Word 8) Channel Number: Specifies the channel (1 – 32) whose status is to be read.
(Word 9) Local PLC - Memory Type: Words 9 and 10 specify the starting point in the client CPU memory where
the Detailed Channel Status words are to be written. The length of the transfer is always 2 words.
(Word 10) Local PLC - Memory Starting Address: Determines the starting address to store the Detailed
Channel Status data. The value entered is the offset (1-based) from the beginning of PLC memory for the
memory type and mode specified in Word 9. This offset is in bits, bytes, or words depending on the mode
specified (for example, if Word 9=16 and Word 10=2, then the starting address will be %I9). Valid ranges of
values depend on the PLC's memory ranges. Make sure this area can contain the 2 words of data without
overwriting other application data.
Note: For the Abort Channel and Retrieve Detailed Channel Status commands, no actual data is
transmitted on the network. Communication occurs between the client CPU and the local
Ethernet Interface only. For these commands, known as "local" commands, the function is
performed locally within the Ethernet Interface and then the COMMREQ Status word is
sent immediately to the CPU.
Monitoring the Detailed Channel Status Words
The Detailed Channel Status words (DCS words) are returned from the Ethernet Interface to the CPU in
response to a Retrieve Detailed Channel Status command from the application program. The first two Detailed
Channel Status bytes report status and errors in the same format as the COMMREQ Status word. See the list of
error codes in Chapter 12.
The second word of the DCS words indicates when the channel is active.
126 PACSystems* RX7i & RX3i TCP/IP Ethernet Communications User Manual
Dec (Hex)
00004 (0004) Length of Channel command Data Block (4 words)
00000 (0000) Always 0 (no-wait mode request)
00008 (0008) Memory Type of COMMREQ status word (%R)
00009 (0009) COMMREQ status word address minus 1 (%R10)
13
00000 (0000) Reserved
00000 (0000) Reserved
02002 (07D2) Retrieve Detailed Channel Status Command number
00005 (0005) Channel number 5
00008 (0008) Local PLC - Memory type to store Detailed Chan. Stat. (%R)
00100 (0064) Local PLC - Starting address (%R100)
GFK-2224Q