27
®
It is suggested that polling intervals not be less than 200 mSec per request. Requesting data
such as burner minutes, system minutes and burner cycles should be kept at a minimum due to
the amount of processing time required to gather that data.
Messages 00, 05, 08, 10, 15, 21 and 26 are unique in that a limited number of successive registers
can be combined with these requests. For example, a request to message 00 can contain up to 6 data
words. The response to this would contain STATUS, MSGN, GSTAT, TIMER, FLAME and LOG-
STAT. If the requested data word count (DAT) were to be 2 then the response would contain STA-
TUS and MSGN only. Message 15, last 6 lockouts, can return data ranging from 1 to 6, with 1
referring to the most recent lockout.
The MSGN being transmitted is a numerical value and must be interpreted by the communicating
device, which actually is an advantage since this can be made to be whatever message text the end
user wants. In other words, it allows for programming custom messages without actually changing
the message in the programmer. Refer to Table 1 for message information.
The Flame-Monitor stores its burner on time and system on time (L1 powered) in minutes. For dis-
play purposes, the programmer converts this to hours. The information being supplied by Modbus
will be the actual time in minutes and it is up to the communicating device to do the conversion.
Since the maximum value stored in the Flame-Monitor is 9,999,999 minutes, the maximum value in
hex therefore is 98967FH and comprises two data words. The maximum cycle count is 999,999 dec-
imal or F423FH, still two data words. As an example, the System on Minutes data is transmitted
from the Flame-Monitor to the interface as high word / low word as shown below:
Note: Data from address 9 cannot be accessed directly.
All values are represented in a HEX or base 16 format.
GSTAT determines the type of value TIMER represents. TIMER can be a running timer such as is
used in purge, a flame signal or meaningless. Only the lower nibble of GSTAT has any value. If this
value is 0 then the TIMER value has no meaning. The value in TIMER is a background minute timer
in the Flame-Monitor and should be ignored. If GSTAT is between 4 and 7, the TIMER represents
the current value flame signal. If GSTAT is a 1, 2, or 3 then TIMER represents a running timer value.
41
6
2nd Most Recent
Lockout Data
47
6
3rd Most Recent
Lockout Data
53
6
4th Most Recent
Lockout Data
59
6
5th Most Recent
Lockout Data
65
6
6th Most Recent
Lockout Data
71
1-3
Input limits and
Expansion Module
registers
Returns input limits state and lower and upper expansion module
(E300) registers. See Table 3
72
1-2
Expansion Module
(E300) registers
Returns lower and upper Expansion Module registers
73
1
Return only upper Expansion Module register
ADDRESS 8
ADDRESS 9
HIGH WORD
LOW WORD
HIGH BYTE
LOW BYTE
HIGH BYTE
LOW BYTE
0
98H
97H
FH
