Chapter 7. Programming SRTP Channel CommandsGFK-2224Q January 2017 133If the COMMREQ status word is updated to 1, the Command Block was processed successfully by the EthernetInterface.If the COMMREQ status word is updated to a value other than 1, an error has occurred in processing theCommand Block. The cause may be:▪ Errors in the Command Block (the Channel command code or parameters), or▪ For an establish command (Establish Read Channel, Establish Write Channel, or Send Information Report),the command parameters were valid but there was an error in establishing a channel.Chapter 11 lists the Major and Minor error codes that may be returned in the COMMREQ status words. Do notuse data received from a server until the COMMREQ status word for that channel is 1 or the Data Transfer bitgoes to 1.Differences between Series 90 and PACSystems SRTP ChannelsThis section lists differences between the Series 90 implementation of SRTP Channels and the PACSystemsimplementation.1. The TCP Connect Timeout for an SRTP Channel on the Series 90 was 90 seconds. For PACSystems, a newSRTP AUP parameter, “SRTP Channel TCP Connect Timeout”, will be added that specifies the amount oftime to wait for a TCP connection to be established: hconn_tout. The default value will be set to 75seconds, and its maximum value is 75 seconds, which is the maximum value we can specify to the currentOS. Minimum value is 10 milliseconds.2. PACSystems has a TCP Linger Period, which is the period of time the OS Network stack hangs onto the TCPresources associated with a connection after it is closed. The TCP resources from a channel that wasstopped will become available again after the 60 second TCP linger period has expired. The Series 90 hadno linger period.3. The Series 90 SRTP Channel implementation performed a normal stopping of the channel on a Run-to-Stoptransition. On PACSystems, a Run-to-Stop transition causes an Abrupt Shutdown, avoiding the TCP Lingerperiod and reducing the chance of exhausting TCP resources when quickly transitioning between Run->Stop and Stop->Run.4. On the Series 90, if an Abort/Abort All Channel COMMREQ is issued, followed by an EstablishRead/Write/Send Info Report Channel COMMREQ before the COMMREQ Status Word for the Abort/Abort Allhas been updated, the Establish Read/Write/Send Information Report was dropped and the COMMREQStatus Word was not updated (it remained zero). For PACSystems, the Establish Read/Write/SendInformation Report COMMREQ is discarded and its COMMREQ Status Word is set to a failure value (A990).That indicates it was discarded because the application logic issued the command while an Abort was inprogress.5. For PACSystems, new COMMREQ Status Codes are defined. See Chapter 11 for details.6. The PACSystems implementation supports Re-tasking to a different remote device (different IP Address).7. The Series 90-70 limited the total number of TCP connections shared between SRTP Client Channels andSRTP Server to 48. TCP connections not shared between SRTP Server and Client, and the maximum TCPConnections allowed for PACSystems are increased as follows:a. maximum of 48 Server TCP connections for Rack-based and RX7i Embedded19b. maximum of 32 Client Channel TCP connections208. CPE330 Embedded Ethernet Interface supports 48 SRTP server connections and 32 client channels.19 32 SRTP server connections for RX3i Embedded Ethernet interface20 16 Client Channel connections for RX3i Embedded Ethernet interface
