To use the ctrl binary for the vulom4 you need to find the binary in you trloii directory on the RIO4.
For 2020/21 E127 this is at
/esr/usr/litv-exp/2020_e127/trloii/trloctrl/fw_426cb99c_trlo/bin_ppc-linux_4.2.2/trlo_ctrl

An example for this DAQ is:

trlo_ctrl --addr=5 --mux-src-scalers (this shows the scaler rates for all vulom I/O)

The complete usage:
  --addr=HEX               Module address (HEX=dummy for dummy).
  --clear-setup            Set all setup to 0 (muxes to wired 0).
  --print-config[=debug]   Show configuration.
  --trig-status[=n]        Print trigger status.  (every n s.)
  --mux-src-scalers[=NAME,n,ptn,rate,limit=i,reset]
                           Dump all MUX source scalers, or per requested NAMEs.
                           Show currently active pattern (ptn, : or *).
                           Difference or (rate).  Every n s (default 1).
                           Limit to #i displays.  Reset scalers.
  --config=FILE            Load command file (to memory only).
  --call=SECTION           Execute SECTION from loaded configuration.
  --cmd="EXPR"             Execute EXPR as an command.
  --show[=setup,dest,src]  Show available setup parameters, etc.
  --tracer[=single]        Soft-scope for TRIG LMU inputs.
  --sampler=ecl-in-N|ecl-io-in-N|lemo-in-N
                           Multi-hit timer-latch (stop with Ctrl+C).
  --rec-mlatch=A,B,[diff]  Multi-hit timer-latch #A,#B,... record to stdout.
  --serial-stamp-rate      Test serial receiver rate. (Avoid with running DAQ).
  --debug[=N]              Debugging of tracer and sampler.
  --addrtest               Run VME test; address readback.
  --ramtest                Run VME test; RAM block write/read.
  --rawread:ADDROFF        Read from VULOM at given VME offset.
  --rawwrite:ADDROFF=VALUE Write to VULOM at given VME offset.