Hello. I'm a programmer at the British Columbia Institute of Technology in Canada. We've got a PV tower with 4 faces (North, East, West, South). This thing was set up a long time ago with Xantrex Suntie XR inverters. All the serial connections are hooked up and I can (mostly) get data from them. I am getting the expected 34-byte bursts every second.

I am extremely grateful for the breakdown of the bytes given in these links:
http://www.solar-guppy.com/forum/viewto ... t=mppthigh
http://www.xantrex.com/forum/forum_post ... 39&KW=STXR

However, I'm a little unsure of the units being used and any conversions required. Are the "Message intpretation constants" given in the first link accurate? Mostly I'm unsure about the negative temperature slopes.

I'm assuming that all other values in Fishbowl are calculated from the known quantities. And I understand that what I'm basically asking for is knowledge of the inner workings of Fishbowl and that perhaps that information shouldn't be publicly disclosed.

Thank you,

Alan Stewart
Research Assistant
Group for Advanced Information Technology (GAIT) Laboratory
British Columbia Institute of Technology
tel: 604-432-8281
web: bcit.ca/appliedresearch/gait

Further to my previous query, I'd also like to know what the possible Fault and Modes settings are. I've seen values of 0x20 and 0x32 (as opposed to the "normal" 0x00 values) so I know they've got to mean something. I'm surprized there aren't data sheet with all this info on them.

Alan Stewart, GAIT, BCIT

Its been awhile since I looked at this stuff, below is a cut&paste from the FishBowl source that should answer your questions, your on your own, but should help your efforts:

On the byte decoding, Sync mode means its a UPG , meaning the comm stream is scanned and when "XR\UPG" is found that the beginning of the data if its an older XR, then the timeout methode is needed


if (SyncMode == true)


{


MsgBuff[BuffPtr] = TMainForm::COMM->ReadByte();
check[0] = check[1];
check[1] = check[2];
check[2] = check[3];
check[3] = check[4];
check[4] = check[5];
check[5] = MsgBuff[BuffPtr];

if ((check[0] == 'X') &&
(check[1] == 'R') &&
(check[2] == '\\') &&
(check[3] == 'G') &&
(check[4] == 'P'))


{
if (BuffPtr == 33) found_sync = true;

BuffPtr = 0;

}

else BuffPtr++;
}
else
{
MsgBuff[BuffPtr] = TMainForm::COMM->ReadByte();
BuffPtr++;
}



if (((BuffPtr == 32) && (SyncMode == false)) ||
((SyncMode == true) && (found_sync == true))) // received complete message

DECODING OF THE COMM STREAM:

if (fault0 == 0) fault0 = MsgBuff[0];

newmodes = MsgBuff[1];
Version = MsgBuff[2];
VAChigh = MsgBuff[4];
VAClow = MsgBuff[5];
FREQhigh = MsgBuff[6];
FREQlow = MsgBuff[7];
AC_WATTShigh = MsgBuff[8];
AC_WATTSlow = MsgBuff[9];
FAULTTIMER = MsgBuff[10];
DC_VOLTS = MsgBuff[11];

if (SyncMode)
{
DC_AMPS = MsgBuff[12];
DC_AMPS_LO = MsgBuff[15];
mppthi = MsgBuff[3];
mpptlo = MsgBuff[13];
}

else
{
DC_AMPS = 0;
mppthi = 0;
mpptlo = 0;
DC_AMPS_LO = 0;
}

DC_VOLTS_LO = MsgBuff[14];
Power_Limit_Hi = MsgBuff[16];
Power_Limit_Lo = MsgBuff[17];
dp_volts_hi = MsgBuff[19];
dp_volts_lo = MsgBuff[20];
dp_amps_hi = MsgBuff[21];
dp_amps_lo = MsgBuff[22];
dp_peak_hi = MsgBuff[23];
dp_peak_lo = MsgBuff[24];
AmbientTemp = MsgBuff[25];
HeatSinkTemp = MsgBuff[26];
dp_volts_hi_p1 = MsgBuff[27];
dp_volts_lo_p1 = MsgBuff[28];
dp_amps_hi_p1 = MsgBuff[29];
dp_amps_lo_p1 = MsgBuff[30];

// Mains AC Voltage

ac_volts = (VAChigh * 256 ) + VAClow;

// Mains Freq

ffreq = (float)((FREQhigh * 256 ) + FREQlow ) / 10;

//DC Volts

dc_volts = (((DC_VOLTS << 8 ) + DC_VOLTS_LO ) >> 5) * .125;

// Instant power

ac_watts = (AC_WATTShigh * 256 ) + AC_WATTSlow ;

// Dc Amps

dc_amps = (DC_AMPS + ((DC_AMPS_LO >> 4 ) * .0625));

// Dc Watts

if (SyncMode) dc_power = dc_amps * dc_volts;
else dc_power = 0;

// dp stuff is the peak delta power reading , cleared every 24 less power cycles
// volts and amps are the values for the dp_peak reading stored

//dp volts

dp_volts = ((dp_volts_hi << 8 ) + dp_volts_lo) * .0625;
dp_volts_p1 = ((dp_volts_hi_p1 << 8 ) + dp_volts_lo_p1) * .0625;

// dp Amps

dp_amps = ((dp_amps_hi << 8 ) + dp_amps_lo) * .0625;
dp_amps_p1 = ((dp_amps_hi_p1 << 8 ) + dp_amps_lo_p1) * .0625;

// dp peak power

dp_peak = (dp_peak_hi * 256) + dp_peak_lo;

// Mppt

mppt_volts = (((mppthi << 8 ) + mpptlo) >> 5) * .125 ;

// Ambient Temp

AmbientTemp = ((((255 - AmbientTemp) * .01953) / .032) + 10);

AmbientTempF = (AmbientTemp * 1.8 ) + 32;

// Heat Sink

HeatSinkTemp = ((((255 - HeatSinkTemp) * .01953) / .032) + 10);

HeatSinkTempF = (HeatSinkTemp * 1.8 ) + 32;

// do math for efficiency stuff

acp = ac_watts;
dcp = dc_power;
if (dcp > 0 ) eff = acp/dcp * 100;
else eff = 0 ;
if (eff > 99.9 )eff = 99.9;

// peak ac watts

if((ac_watts > ac_watts_peak) && (ac_watts < 2800 )) ac_watts_peak = ac_watts;


// running total math

ac_power_total = ac_power_total + ((AC_WATTShigh << 8 ) + AC_WATTSlow);
ac_kwh = ac_power_total / 3600;

if (FAULTTIMER == 0 )
{
online_seconds++;
}


if (online_seconds == 60 )
{
online_seconds = 0;
online_minutes++;
}

if (online_minutes == 60)
{
online_minutes = 0;
online_hours++;
}


}

FAULT DECODING


if (fault0 == 255) strcpy(fault_text,"AC over 264 vac");
else if(fault0 == 253) strcpy(fault_text,"AC under 211 vac");
else if(fault0 == 251) strcpy(fault_text,"Line freq over 60.5");
else if(fault0 == 249) strcpy(fault_text,"Line freq under 59.3");
else if(fault0 == 247) strcpy(fault_text,"DC input volts over 125 VDC");
else if(fault0 == 245) strcpy(fault_text,"DC input volts under 40VDC");
else if (newmodes & 0x01)

{
strcpy(tempstr,"");
maxpower = (Power_Limit_Hi * 256) + Power_Limit_Lo;
strcpy(fault_text,"Tempature derating enabled , maximum allowed power = ");
itoa(maxpower, tempstr, 10);
strcat(fault_text,tempstr);
strcat(fault_text," Watts");
}

else if(fault0 != 0)

{
strcpy(tempstr,"");
itoa(fault0, tempstr, 10);
strcpy(fault_text,"Fault detected , code = ");
strcat(fault_text,tempstr);
}
else if((fault0 == 0) & (FAULTTIMER != 0 ) )

{
strcpy(tempstr,"");
strcpy(fault_text,"Offline, connect in ");
itoa(FAULTTIMER*2, tempstr, 10);
strcat(fault_text,tempstr);
strcat(fault_text," seconds");
}


else strcpy(fault_text,"Normal operation");

This is excellent. I'm sure I'll be able to figure out what I need from your code. Well, once I do a quick search'n'replace and change all the "Cool" guy with shades into the proper "8 )", that is.

Thank you!

Alan STewart, GAIT, BCIT