Chapter 7. Programming SRTP Channel Commands120 PACSystems* RX7i & RX3i TCP/IP Ethernet Communications User Manual GFK-2224QEstablish Write Channel (2004)The Establish Write Channel command requests that a channel be connected to a remote PLC and that datafrom the local PLC be transferred (periodically) to the remote PLC. The Command Block specifies the period, thenumber of writes to the server (remote PLC) to perform, and the timeout allowed in waiting for each transfer tocomplete. The first write is performed immediately, regardless of the period specified.Example Command BlockEstablish a write channel (Channel 6) to a remote PLC at IP address 10.0.0.1. Return the COMMREQ Status wordto %R10. Write local PLC registers %R50–%R57 to remote PLC registers %R100–%R107. Repeat the writeindefinitely, once every 7 seconds, with a timeout of 500ms for each write.Dec (Hex)Word 1 00017 (0011) Length of Channel command Data Block (17–25 words)Word 2 00000 (0000) Always 0 (no-wait mode request)Word 3 00008 (0008) Memory type of COMMREQ status word (%R)Word 4 13 00009 (0009) COMMREQ status word address minus 1 (%R10)Word 5 00000 (0000) ReservedWord 6 00000 (0000) ReservedWord 7 02004 (07D4) Establish Write Channel command numberWord 8 00006 (0006) Channel number (6)The term localPLC is used hereto identify theclient PLC—thePLC that initiatesthecommunicationsrequest.Word 9 00000 (0000) Number of write repetitions (write indefinitely)Word 10 00003 (0003) Time unit for write period (3=seconds)Word 11 00007 (0007) Number of time units for write period (every 7 seconds)Word 12 00050 (0032) Timeout for each write (500ms)Word 13 00008 (0008) Local PLC - Memory type from which to write data (%R)Word 14 00050 (0032) Local PLC - Starting address from which to write data(%R50)The term remotePLC is used hereto identify theserver PLC—thePLC that respondsto thecommunicationsrequest.Word 15 00008 (0008) Remote PLC - Memory type at which to store data (%R)Word 16 00100 (0064) Remote PLC - Starting address at which to store data(%R100)Word 17 00008 (0008) Remote PLC - Number of memory units (8 registers)Word 18 00001 (0001) Remote PLC - Network Address type (IP address)Word 19 00004 (0004) Remote PLC - Network Address length in words (4)Word 20 00010 (000A) Remote PLC - Register 1 of IP address (10)Word 21 00000 (0000) Remote PLC - Register 2 of IP address (0)Word 22 00000 (0000) Remote PLC - Register 3 of IP address (0)Word 23 00001 (0001) Remote PLC - Register 4 of IP address (1)Word 24–27 Remote PLC - Program Name (needed for access toremote %P or %L) (zero-terminated and padded)Word 28–31 Remote PLC - Program Block (needed for access to remote%L) (zero-terminated and padded)(Word 7) Channel Command Number: Word 7 requests that a write channel be set up. If the command isprocessed successfully, it will result in attempting the specified number of transfers from the client to theserver.(Word 8) Channel Number: Word 8 specifies the channel to be used for the write. This value must be in therange of 1–32. If the channel number is out of range, a command error indication will be placed in theCOMMREQ Status word. If the channel number is the same as a channel already in use, the channel will be re-tasked to perform this new command.
