LDP6-CCDC
Serial Communications Option Card
M4539-0607
1
INSTALLING AN OPTION CARD
Caution: The option and main circuit cards contain static sensitive
components. Before handling the cards, discharge static charges
from your body by touching a grounded bare metal object. Ideally,
handle the cards at a static controlled clean workstation. Also,
handle the cards by the edges only. Dirt, oil or other contaminants
that may contact the cards can adversely affect circuit operation.
Warning: Exposed line voltage exists on the circuit boards. Remove
all power to the meter AND load circuits before accessing the unit.
1. Remove the main assembly from the rear of the case. Squeeze the finger
holds on the rear cover, or use a small screwdriver to depress the side
latches to release it from the case. It is not necessary to separate the rear
cover from the main circuit card.
2. Locate the option card connector for the type of option card to be installed.
Hold the unit by the rear connector, not the display board, when installing
an option card.
3. Install the option card by aligning the option card connector with the slot
bay in the rear cover. The cards are keyed by position with different main
board connector locations. Be sure the connector is fully engaged and the
tab on the option card rests in the alignment slot on the display board.
4. Slide the assembly back into the case. Be sure the rear cover latches fully
into the case.
5. Apply the option card label to the bottom side of the meter. Do not cover
the vents on the top surface of the meter .The surface of the case must be
clean for the label to adhere properly. Apply the label to the area designated
by the large case label.
DESCRIPTION
This bulletin serves as a guide for the installation, configuration and
operation of the RS232 and RS485 cards for the DP63 family of meters. Only
one communication card can be used at a time.
The meter can be fitted with up to three different option cards. The slot bays
of the option cards are dedicated to a particular card function. The option card
functions are: serial communications, analog output and setpoint output. Only
one card from each function category can be installed into the meter.
TOP VIEW
SPECIFICATIONS
DP63700 Isolation For Both Cards:
Isolation To Sensor Common: 1400 Vrms for 1 min.
Working Voltage: 125 V
Isolation To User Input Common: 500 Vrms for 1 min.
Working Voltage: 50 V
RS485 Communication Card
Type: RS485 multi-point balanced interface
Isolation To Sensor & User Input Commons: 500 Vrms for 1 min.
Working Voltage: 50 V. Not Isolated from all other commons.
Baud Rate: 300 to 19.2k
Data Format: 7/8 bits; odd, even, or no parity
Bus Address: 0 to 99, max 32 meters per line
Transmit Delay: Selectable; 2 - 50 msec or 50 - 100 msec
RS232 Communication Card
Type: RS232 half duplex
Isolation To Sensor & User Input Commons: 500 Vrms for 1 min.
Working Voltage: 50 V. Not Isolated from all other commons.
Baud Rate: 300 to 19.2k
Data Format: 7/8 bits; odd, even or no parity
LP0685X
INSTRUCTION
SHEET
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2
RS232 Communications
RS232 is intended to allow only two devices to communicate over distances up
to 50 feet. Data Terminal Equipment (DTE) transmits data on the Transmitted
Data (TXD) line and receives data on the Received Data (RXD) line. Data
Computer Equipment (DCE) receives data on the TXD line and transmits data on
the RXD line. This meter emulates a DTE. If the other device connected to the
meter also emulates a DTE, the TXD and RXD lines must be interchanged for
communications to take place. This is known as a null modem connection. Most
printers emulate a DCE device while most computers emulate a DTE device.
Some devices cannot accept more than two or three characters in succession
without a pause in between. In these cases, the meter employs a busy function.
As the meter begins to transmit data, the RXD line (RS232) is monitored to
determine if the receiving device is “busy”. The receiving device asserts that it
is busy by setting the RXD line into a space condition (logic 0). The meter then
suspends transmission until the RXD line is released by the receiving device.
RS485 Communications
The RS485 communication standard allows the connection of up to 32
devices on a single pair of wires, distances up to 4,000 ft. and data rates as high
as 10M baud. The same pair of wires is used to both transmit and receive data.
An RS485 bus is therefore always half-duplex, that is, data cannot be received
and transmitted simultaneously.
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DATA BIT
PARITY BIT
300 1200
600 2400
192004800
9600
7 8
Odd EVEN NO
It is necessary to match the meter’s serial communications parameters to the
host’s parameters before communications can be established. This is
accomplished by using the front panel keys to enter
.
MODULE 7 - SERIAL COMMUNICATIONS PARAMETERS (4S-)
PARAMETER MENU
BAUD RATE
Indicates Program Mode Alternating Display.
Factory Settings are shown.
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Parameter
Selection/Value
WIRING CONNECTIONS
Terminal Block Connection Figure
Extended Comms Connection Figure
Extended Comms Connection Figure
Terminal Block Connection Figure
Set the baud rate to match that of other serial communications equipment.
Normally, the baud rate is set to the highest value that all of the serial
communications equipment is capable of transmitting.
Select either 7 or 8 bit data word lengths. Set the word
length to match that of other serial communication equipment. Since the meter
receives and transmits 7-bit ASCII encoded data, 7 bit word length is sufficient
to request and receive data from the meter.
Set the parity bit to match that of the other serial
communications equipment used. The meter ignores the parity when receiving
data, and sets the parity bit for outgoing data. If no parity is selected with 7-bit
word length the meter transmits and receives data with 2 stop bits. (For
example: 10 bit frame with mark parity)
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3
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ABBREVIATED PRINTING
PRINT OPTIONS
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METER ADDRESS
0 to 99
YES NO
YES NO
Input Value
Max and Min Values
Total Value
Setpoint values*
Enter the serial node address. With a single unit on a bus, an address is not
needed and a value of zero can be used (RS232 applications). Otherwise, with
multiple bussed units, a unique address number must be assigned to each meter.
The node address applies specifically to RS485 applications.
Select abbreviated transmissions (numeric only) or full field transmission.
When the data from the meter is sent directly to a terminal for display, the extra
characters that are sent identify the nature of the meter parameter displayed. In
this case, select
. When the data from the meter goes to a computer, it may be
desirable to suppress the node address and mnemonic when transmitting. In this
case, set this parameter to
.
- Enters the sub-menu to select those meter parameters to appear in the
block print. For each parameter in the sub-menu select for the parameter to
appear with the block print, and to disable the parameter.
*Setpoints 1-4 are setpoint plug-in card dependent.
Sending 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, numerical data (if writing data to the
meter) followed by a the command terminator character * or $.
Command Chart
Register Identification Chart
Command Description Notes
N
Node Address
Specifier
Address a specific meter. Must be followed by
one or two digit node address. Not required
when node address = 0.
T Transmit Value (read)
Read a register from the meter. Must be
followed by register ID character.
V Value change (write)
Write to register of the meter. Must be
followed by register ID character and numeric
data.
R Reset
Reset a register or output. Must be followed
by register ID character
P
Block Print Request
(read)
Initiates a block print output. Registers are
defined in programming.
ID Value Description
Register
ID
Applicable Commands/Comments
A Input INP
B Total TOT
(Reset command resets total to
zero)
C Max Input MAX
(Reset command resets MAX to
current reading)
D Min Input MIN
(Reset command resets MIN to
current reading)
E Setpoint 1 SP1
(Reset command resets the
setpoint output)
F Setpoint 2 SP2
(Reset command resets the
setpoint output)
G Setpoint 3 SP3
(Reset command resets the
setpoint output)
H Setpoint 4 SP4
(Reset command resets the
setpoint output)
I
Analog Output
Register
AOR (Applies to manual mode)
J
Control Status
Register
CSR
T, P
T, P, R
T, P, R
T, P, R
T, P, V, R
T, P, V, R
T, P, V, R
T, P, V, R
T, V
T, V
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 according to the selections made in print options.
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 timing diagram figure for differences of *
and $ terminating characters.
Command String Examples:
1. Node address = 17, Write 350 to Setpoint 1, response delay of 2 msec min
String: N17VE350$
2. Node address = 5, Read Input value, response delay of 50 msec min
String: N5TA*
3. Node address = 0, Reset Setpoint 4 output, response delay of 50 msec min
String: RH*
Sending Numeric Data
Numeric data sent to the meter must be limited to 5 digits (-19,999 to 99,999).
If more than 5 digits are sent, the meter accepts the last 5. 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 = 0.0 and 25 is written to a register.
The value of the register is now 2.5 In this case, write a value = 25.0).
Note: Since the meter does not issue a reply to value change commands, follow
with a transmit value command for readback verification.
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