Thanks Eric for the suggestions! For the terminator character error message, I get : Set EOS failed: L0 setOutputEos not implemented
when enabling asynOctetSetInputEos("L0",-1,"\n") and asynOctetSetOutputEos("L0",-1,"\n").
Good point about the double cast on atof - there was no reason for it, have removed it. I tried turning on more diagnostics but weirdly enough don't even see any communication with the device in terms of bytes being read or written. However I can see the frequency change on the device so I know that setting the frequency works. Here's the output from the ioc:
cd /home/admx/admxepics/iocs/SdCarLO
## Register all support components
dbLoadDatabase "dbd/SdCarLO.dbd"
SdCarLO_registerRecordDeviceDriver pdbbase
prologixGPIBConfigure("L0", "10.95.101.74:1234")
asynOctetSetInputEos("L0",-1,"\n")
asynOctetSetOutputEos("L0",-1,"\n")
Set EOS failed: L0 setOutputEos not implemented
asynSetTraceIOMask("L0", -1, 0x2)
asynSetTraceMask("L0", -1, 0xFF)
## Load record instances
cd /home/admx/admxepics/devices/ag83620b
dbLoadRecords("db/devAG83620B.db","SIGGEN=SDCARLO, L=0, A=19")
cd /home/admx/admxepics/iocs/SdCarLO/iocBoot/iocSdCarLO
iocInit
############################################################################
## EPICS R3.14.12.4 $Date: Mon 2013-12-16 15:51:45 -0600$
## EPICS Base built May 20 2014
############################################################################
## Start any sequence programs
#seq sncxxx,"user=admxHost"
epics> 2014/12/10 12:08:57.985 SDCARLO:GET:FREQ read status "" nin 0
2014/12/10 12:08:57.985 SDCARLO:GET:FREQ error.
2014/12/10 12:08:57.985 asynManager::portThread port=L0 callback
epics> dbpf SDCARLO:SET:FREQ 12
DBR_DOUBLE: 12
epics> 2014/12/10 12:09:12.743 SDCARLO:GET:FREQ read status "" nin 0
2014/12/10 12:09:12.743 SDCARLO:GET:FREQ error.
dbtr SDCARLO:GET:FREQ
ACKS: INVALID ACKT: YES ADEL: 0 ALST: 0
AOFF: 0 ASG: ASLO: 1 BKPT: 00
DESC: Query Frequency ouput MHz DISA: 0 DISP: 0
DISS: NO_ALARM DISV: 1 DTYP: AG83620B EGU: MHz
EGUF: 0 EGUL: 0 EOFF: 0 ESLO: 1
EVNT: 0 FLNK:CONSTANT 0 HHSV: NO_ALARM HIGH: 0
HIHI: 0 HOPR: 0 HSV: NO_ALARM HYST: 0
INIT: 0 INP:GPIB_IO #L0 A19 @4 CPP LALM: 0
LBRK: 0 LCNT: 0 LINR: NO CONVERSION LLSV: NO_ALARM
LOLO: 0 LOPR: 0 LOW: 0 LSV: NO_ALARM
MDEL: 0 MLST: 0 NAME: SDCARLO:GET:FREQ
NSEV: NO_ALARM NSTA: NO_ALARM ORAW: 0 PACT: 1
PHAS: 0 PINI: YES PREC: 0 PRIO: LOW
PROC: 0 PUTF: 0 ROFF: 0 RPRO: 0
RVAL: 0 SCAN: Passive SDIS:CONSTANT SEVR: INVALID
SIML:CONSTANT SIMM: NO SIMS: NO_ALARM SIOL:CONSTANT
SMOO: 0 STAT: READ SVAL: 0
TIME: 2014-12-10 12:09:12.743268858 TPRO: 0 TSE: 0
TSEL:CONSTANT UDF: 1 VAL: 0
epics> 2014/12/10 12:09:22.508 SDCARLO:GET:FREQ read status "" nin 0
2014/12/10 12:09:22.508 SDCARLO:GET:FREQ error.