RECEIVING DATA FROM THE IMD1
Data is transmitted from the indicator whenever a “T” or “P” command is
received via serial communications or a remote input, E1-CON or optional
E2-CON pin is programmed for print request, is activated. If the abbreviated
transmission was programmed, just data will be transmitted with no built-in
delay. (If full transmission is programmed, then there is a 400 msec min. to 800
msec max. delay built in to the string.) A data string transmission is shown below.
The first two characters transmitted are the unit address number, unless it is
zero, in which case it is left blank. Then two blank spaces are sent. The next
three characters are the abbreviation for the value (mnemonics), which is then
followed by a blank. The actual data is transmitted next. The field is right
justified with leading zeros. Negative numbers are indicated by a minus sign
fixed next to the identifier. A carriage return and a line feed are transmitted
next. For various reasons, “extra” characters are added onto the end of the
above character string. (These characters could be and are used for control or
signaling purposes.) These characters are:
< CR> sent after single line transmissions from IM unit
< SP> < CR> < LF> sent after “last line of a block” transmission from IM unit
For a “T” command or after each “line of a block” transmission, no
additional characters are sent. If the abbreviated transmission is selected, the
address, mnemonics, and any blank spaces (first eight characters) are not
transmitted (the data strings are left justified in this case).
If the transmitted data is overrunning the peripheral’s buffer, the receive
channel to the indicator may be used for handshaking purposes. As a
consequence of this, even if the indicator is to transmit only (ex. to a printer),
current must be flowing in the receive channel to allow transmission.
Examples of transmissions are as follows:
2 TOT-125.75 < CR><LF> full transmission
-125.75 < CR><LF> abbreviated transmission
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