Apollo Intelligent Meter Series IMY Manual de usuario descargar pdf (Pagina 32)

RECEIVING DATA FROM THE IMY

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.

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 INP -125.7F < CR> < LF > full transmission

-125.7 < CR> < LF > abbreviated transmission

CURRENT LOOP INSTALLATION

WIRING CONNECTIONS

When wiring the 20 mA current loop, remove the bottom terminal block

(TBA), located on the rear of the unit. Refer to the numbers listed with the

terminal descriptions below or those located on the label. It is recommended

that shielded (screened) cable be used for serial communications. This unit

meets the EMC specifications using Alpha #2404 cable or equivalent. There

are higher grades of shielded cable, such as four conductor twisted pair, that

offer an even higher degree of noise immunity. Install each wire in its proper

location on the terminal block. When all connections are made, replace the

terminal block into its proper location.

SERIAL TERMINAL DESCRIPTIONS

8. PRINT REQ. - The Print Request terminal is pulled low to activate the unit

to transmit data according to the print function selected in Program Module

#7 (Reference Programming Module #7 for more details). In order for a

print request function to occur, E1-CON (TBA #4) or E2-CON (TBA #8)

must be programmed for print request. Note: In order to guarantee a

print-out, the programmed E-CON pin must be held low for at least 20

msec. If this time exceeds 800 msec, a second print-out may occur.

9. -20 mA SRC. - 20 mA current source return path for the transmit loop.

Current flows into this pin.

10. SI+ (Serial In+) -

11. SI- (Serial In-) -

The unit receives commands on the SI terminals. They are connected in

series with the transmit or output terminals of the device to be connected.

12. SO+/+20 mA SRC. (Serial Out+) - 20 mA current source for the transmit

loop (internally connected).

13. SO- (Serial Out-) -

The unit transmits the requested data on the SO terminals. They are

connected in series to the receive input of the device to be connected.

Note: The Serial Input terminals must be held in the mark condition (current

flowing) in order for the unit to respond to a Print Request terminal activation.

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Apollo Intelligent Meter Series IMY Manual de usuario Pagina 32

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