Experimental Physics and
Industrial Control System

James F Ross <[email protected]> · Thu, 21 Feb 2013 11:41:45 -0500

Hello everyone,
As I mentioned in a previous email I'm trying to write an IOC that
controls a wiener PL508 crate via snmp.  I have one that controls a
PL512 crate and I'm trying to understand it so I can write an IOC for
the PL508.

At the moment, I'm focusing on how the .db files get the information
from snmp.  The following record is a good example:
record(ai, "HFT:PXL:U$(Ch):GetDemandVoltage")
{
    field(DTYP,"asynFloat64")
    field(INP,"@asyn($(IP) $(Ch) .1) Demand_Voltage")
    field(SCAN,"5 second")
    field(LINR,"LINEAR")
}

Where Ch can be 0 through 11 and IP is the IP address of the crate.

I believe that the key is this field:
field(INP,"@asyn($(IP) $(Ch) .1) Demand_Voltage")

This should correspond to one of the following variables (obtained via
snmpwalk).  I think the first is most likely the variable that the
field gets its input from.
WIENER-CRATE-MIB::outputVoltage.u0 = Opaque: Float: 4.500000 V
WIENER-CRATE-MIB::outputMeasurementSenseVoltage.u0 = Opaque: Float: 0.000000 V
WIENER-CRATE-MIB::outputMeasurementTerminalVoltage.u0 = Opaque: Float:
0.000000 V

Does anyone know where a good guide to using asyn with snmp would be?
Or perhaps a general epics/snmp guide?  I just need to know how
"@asyn($(IP) $(Ch) .1) Demand_Voltage" points to outputVoltage.u0 and
what I should put in other INP fields for other crate variables.

Thanks!
James

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System