PMDG B777X Offset 65B8 (COMM_ReceiverSwitches[3])

[ckovoor]

Hi Pete,

I am having a problem with reading bit flags for certain COMM receivers on the Audio Control Panel. They are described in the Offset Mapping for PMDG777X document:
 

Comm Systems: 0=VHFL 1=VHFC 2=VHFR 3=FLT 4=CAB 5=PA 6=HFL 7=HFR 8=SAT1 9=SAT2 10=SPKR 11=VOR/ADF 12=APP

65B8 (3) (BYTE x 3): COMM_ReceiverSwitches[3]: 0=capt, 1=F/O, 2=observer
values: Bit flags for selector receivers 0...12 (VHFL..APP) as listed above
 
65BB (1) (BYTE): COMM_OBSAudio_Selector: 0 CAPT 1 NORMAL 2 F/O

 

 

Okay, so I understand that 65B8 is reserved for Capt, 65B9 for F/O and 65BA for Observer.
But each of these offset (bytes) contain only 8 bits, so how could I read bits 9 through 13 (flags for receivers 8 through 12)?

In fact, if I try to read one of these, as for example bit flag 9 below, I do not get any return (as I would expect, since UB can only go as far as 255 :???: ):

function COMM_Rcvr_Switch_FO_SAT1(offset, value)
    if logic.And(ipc.readUB("65B9"), 256) ~= 0 then
        ipc.writeLvar("L:COMM_Rcvr_Switch_FO_SAT1", 1)
    else ipc.writeLvar("L:COMM_Rcvr_Switch_FO_SAT1", 0)
    end
end

event.offset("65B9", "UB", "COMM_Rcvr_Switch_FO_SAT1")

I should mention that I can read the first 8 bit flags with this method.

 

Would you please clarify this for me? My understanding is that a particular offset (byte) can contain a maximum of 8 bit flags, but the documentation indicates 13 within each.

Thanks for your help.

Chakko.

[Pete Dowson]

Hi Pete,

I am having a problem with reading bit flags for certain COMM receivers on the Audio Control Panel. They are described in the Offset Mapping for PMDG777X document:

 

 

 

Okay, so I understand that 65B8 is reserved for Capt, 65B9 for F/O and 65BA for Observer.

But each of these offset (bytes) contain only 8 bits, so how could I read bits 9 through 13 (flags for receivers 8 through 12)?

In fact, if I try to read one of these, as for example bit flag 9 below, I do not get any return (as I would expect, since UB can only go as far as 255 :???: ):

function COMM_Rcvr_Switch_FO_SAT1(offset, value)
    if logic.And(ipc.readUB("65B9"), 256) ~= 0 then
        ipc.writeLvar("L:COMM_Rcvr_Switch_FO_SAT1", 1)
    else ipc.writeLvar("L:COMM_Rcvr_Switch_FO_SAT1", 0)
    end
end

event.offset("65B9", "UB", "COMM_Rcvr_Switch_FO_SAT1")

I should mention that I can read the first 8 bit flags with this method.

 

Would you please clarify this for me? My understanding is that a particular offset (byte) can contain a maximum of 8 bit flags, but the documentation indicates 13 within each.

Thanks for your help.

Chakko.

 

 

Good catch! Please ask PMDG 777X support this very good question. Their documentation definitely shows:

 

unsigned char COMM_ReceiverSwitches[3]; // array: 0=capt, 1=F/O, 2=observer  values: Bit flags for selector receivers 0...12 (VHFL..APP) as listed above

 

The unsigned char value is 1 byte (8 bits).

 

Pete