9-3
9.2 POINT-TO-POINT CONTINUOUS MODE
As described before, the meter transmits its different measurement values in strings of
characters continuously on the bus. The length of the string is variable and is
controlled by two menu items: “DAt.FMt” and “bUS.FMt” (see Sections 10.12 and
10.13). The time between consecutive transmission is also controlled by another menu
item: “SERCNt”. This item is in units of “numbers of readings” (Section 10.20).
9.2.1 METER’S RESPONSE TIME
This is the difference in time from the moment when the Serial Count (“SERCNt”)
value is reached to the time of transmission of the first character of the data string.
TABLE 9.2 READING RATE FOR COMMUNICATION
Sample Rate Process (100mV) Rate (ms) TC (K type) Rate (ms)
0 (slow) 7(135) 7(135)
1 14(68) 14(68)
2 27(36) 27(36)
3 52(19) 33(30)
4 71(14) 33(30)
5 (fast) 71(14) 33(30)
Test with Communication (Baud Rate at 19200 bps, Continuous Mode)
Although transmission’s program delay seems longer than chunk
transmission, in most cases total transmission time will be shorter, especially
using 19200 baud rate.
9.2.2 COMMUNICATING WITH THE METER WHEN IN CONTINUOUS MODE
If the meter is in point-to-point continuous mode, it ignores any transmitting command.
On the other hand, transmitting “X-OFF” character (13 Hex) which is equivalent to the
“RTS line false” will halt continuous transmission. Transmitting “X-ON” character
(11 hex) or making “RTS line true” will resume continuous transmission. Specifically, if
command “^AE” is transmitted, it will cause the meter to switch to COMMAND mode.
To be able to communicate with the meter when in Continuous Mode, do the following:
1. Transmit “X-OFF” character or make “RTS” line false.
2. Transmit “^AE” command. Now your meter is in Command Mode.
3. Do the communication with the meter.
4. Use “P1C” command to change BUS FORMAT (see Section 10.13) i.e., change
bit #4 of “bUS FMt” from 1 to 0 to go back to Continuous Mode
9. Meter Bus Response
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