14

Sending Serial Commands and Data

When sending commands to the meter, a string containing at least one

command character must be constructed. A command string consists of a

command character, a value identifier, and numerical data (if writing data to the

meter) followed by a command terminator character, * or $.

Command Chart

Register Identification Chart

ID

Value Description

MNEMONIC

Applicable

Commands

Transmit Details (T and V)

A

Counter A

CTA

T, V, R

8 digit positive/7 digit

negative (with minus sign)

B

Counter B

CTB

T, V, R

7 digit, positive only

C

Rate

RTE

T

6 digit, positive only

D

Scale Factor A

SFA

T, V

6 digit, positive only

E

Scale Factor B

SFB

T, V,

6 digit, positive only

F

Setpoint 1

(Reset Output 1)

SP1

T, V, R

per setpoint Assignment,

same as Counter or Rate

G

Setpoint 2

(Reset Output 2)

SP2

T, V, R

per setpoint Assignment,

same as Counter or Rate

H

Counter A Count

Load Value

CLD

T, V

8 digit positive/7 digit

negative (with minus sign)

Command String Construction

The command string must be constructed in a specific sequence. The meter

does not respond with an error message to illegal commands. The following

procedure details construction of a command string:

1. The first 2 or 3 characters consist of the Node Address Specifier (N) followed

by a 1 or 2 character node address number. The node address number of the

meter is programmable. If the node address is 0, this command and the node

address itself may be omitted. This is the only command that may be used in

conjunction with other commands.

2. After the optional address specifier, the next character is the command character.

3. The next character is the register ID. This identifies the register that the

command affects. The P command does not require a register ID character. It

prints all the active selections chosen in the Print Options menu parameter.

4. If constructing a value change command (writing data), the numeric data is

sent next.

5. All command strings must be terminated with the string termination characters

* or $. The meter does not begin processing the command string until this

character is received. See Command Response Time section for differences in

meter response time when using the * and $ terminating characters.

Command String Examples:

1. Node address = 17, Write 350 to the Setpoint 1 value

String: N17VF350*

2. Node address = 5, Read Counter A, response time of 50 msec min

String: N5TA*

3. Node address = 0, Reset Setpoint 1 output

String: RF*

4. Node address = 31, Request a Block Print Output, response time of 2 msec min

String: N31P$

Transmitting Data to the Meter

Numeric data sent to the meter must be limited to transmit details listed in the

Register Identification Chart. Leading zeros are ignored. Negative numbers

must have a minus sign. The meter ignores any decimal point and conforms the

number to the scaled resolution. (For example: The meter’s scaled decimal point

position is set for 0.0 and 25 is written to a register. The value of the register is

now 2.5. In this case, write a value of 250 to equal 25.0).

Note: Since the meter does not issue a reply to value change commands, follow

with a transmit value command for readback verification.

Receiving Data From The Meter

Data is transmitted from the meter in response to either a transmit command

(T), a block print request command (P) or a User Input print request. The

response from the meter is either a full field transmission or an abbreviated

transmission, depending on the selection chosen in Module 5.

Full Field Transmission

Byte

Description

1, 2

2 byte Node Address field [00-99]

3

<SP> (Space)

4-6

3 byte Register Mnemonic field

7-18

12 byte data field; 10 bytes for number, one byte for sign,

one byte for decimal point

19

<CR> (carriage return)

20

<LF> (line feed)

21

<SP>* (Space)

22

<CR>* (carriage return)

23

<LF>* (line feed)

* These characters only appear in the last line of a block print.

The first two characters transmitted are the meter address. If the address

assigned is 0, two spaces are substituted. A space follows the meter address

field. The next three characters are the register mnemonic, as shown in the

Register Identification Chart.

The numeric data is transmitted next. The numeric field (bytes 7 to 18) is 12

characters long. When a requested counter or rate value exceeds the meter’s

display limits, an * (used as an overflow character) replaces a space in byte 7.

Byte 8 is always a space.

The remaining ten positions of this field consist of a minus sign (for negative

values), a floating decimal point (if applicable), and eight positions for the

requested value. The data within bytes 9 to 18 is right-aligned with leading

spaces for any unfilled positions.

The end of the response string is terminated with a <CR> and <LF>. After

the last line of a block print, an extra <SP>, <CR> and <LF> are added to

provide separation between the print blocks.

Initiates a block print output. Registers in the

print block are selected in Print Options.

Block Print Request

(read)

P

Reset a count value or setpoint output. Must

be followed by a register ID character

Reset

R

Write to register of the meter. Must be

followed by a register ID character and

numeric data.

Value Change (write)

V

Read a register from the meter. Must be

followed by a register ID character.

Transmit Value

(read)

T

Address a specific meter. Must be followed

by one or two digit node address. Not

required when node address = 0.

Node (meter)

Address Specifier

N

Notes

Description

Command

Copy Procedure:

1. Connect the master and receiver using the appropriate copy cable.

2. Apply power to the meters. The receiving meter must be operating in the

normal display mode (not programming mode).

3. On the master meter, enter programming mode and proceed to the Copy

4. During the copy process (~ 2 sec.), the master meter displays an upload

This indicates successful communication between the master and receiver. If

the receiver message is not displayed, be sure the proper cable is connected.

5. When copying is complete, the receiver displays the power-up sequence and

returns to normal operating mode, programmed with all the same settings as

another receiver for copying.

SEL

RST

UP-LOAd

dn-LOAd

SEL

RST

MASTER

RECEIVER