ringdup_scn is SCNL compatible and has a blocking capability, see .d file below:
# ringdup_scn configuration file
#
#
MyModuleId MOD_RINGDUP_SCN # module id for this program
InRing WAVE_RING # transport ring to use for input
OutRing EXPPT_RING # transport ring to use for output
HeartBeatInt 30 # EW internal heartbeat interval (sec)
LogFile 1 # If 0, don't write logfile; if 1, do
# if 2, write to module log but not to
# stderr/stdout
#
# Logos of messages to export to client systems
# Installation Module Message Type
GetMsgLogo INST_WILDCARD MOD_WILDCARD TYPE_TRACEBUF2
MaxMsgSize 4096 # maximum size (bytes) for input/output msgs
RingSize 100 # max# messages in outgoing circular msg buffer
# List of station/channel/network/loc codes to duplicate.
#--------------------------------------------------------
# NOTE: Send_scn and Send_scn_remap commands are now obsolete, and
# have been replaced with Send_scnl and Send_scnl_remap (which
# include the location code field). If the old commands are used,
# ringdup_scn sets the location code field to * (wildcard).
#
# Use any combination of Send_scnl (to send data as-is) and
# Send_scnl_remap (to change the SCNL on the fly) commands.
# Use * as a wildcard for any field. A wildcard in the
# "map to" fields of Send_scnl_remap means that field will
# not be renamed.
# Use the Block_scnl command (works with both wildcards
# and not, but only makes sense to use with wildcards) to block
# any specific channels that you don't want sent.
# Note, the Block commands must precede any wildcard commands for
# the blocking to occur.
#
# send SCNL map to SCNL
Block_scnl BOZ LHZ US * # block this specific channel
Send_scnl JMP ASZ NC 01 # send this specific channel
Send_scnl JPS * NC * # send all components of JPS NC
Send_scnl_remap JGR VHZ NC -- * EHZ * * # change component code only
Send_scnl_remap CAL * NC * ALM * * * # send all component of CAL, but
# change the site code to ALM