Honeywell VC4 User Manual page 146

Response Packet from instrument:
Command Code (0x37) - 1 byte
VC4™ Date - 2 bytes
VC4™ Time - 2 bytes (If point is Disabled/Invalid/locked out, fill with zeroes)
MDA Gas Abbr. - 6 bytes (not null terminated)
Format Code - 1 byte
Flow Rate - 2 bytes (current flow)
TWA Start Date - 2 bytes
TWA Start Time - 2 bytes
TWA End Date -2 bytes
TWA End Time - 2 bytes
TWA Conc. - 2 bytes
Last Conc. - 2 bytes (last reported conc.)
Alarm Status - 1 byte (0 none, 1 or 2 level) (Fill for all conditions) Status - 1 byte
0x00 = Data valid
0x01 = Point Disabled (no data filled)
0x02 = Point Locked Out (no data filled)
0x04 = No TWA calculated
0x08 = No concentration available
0x10 = Alarm Simulation mode active
0xff = Invalid data
Get TWA Time - 0x38
This command queries the three TWA output time in a 24-hour format. Each of the TWA times
are eight hours apart.
Command packet to instrument:
Command Code (0x38) - 1 byte
Response packet from instrument:
Command Code (0x38) - 1 byte
VC4™ Date - 2 bytes
VC4™ Time - 2 bytes
TWA time 1 - 2 bytes
TWA time 2 - 2 bytes
TWA time 3 - 2 bytes
VC4™ 146 User Manual