Instruction Manual for Mercury Electronic Precision Balances

General Description

This instruction manual provides details for four electronic precision balance models: EX-300A, EX-3000A, EY-320A, and EY-3200A.

EX-A Series Balances

The EX-A series are single-range, high-precision top-loading balances with a resolution of 1/300,000 and a temperature coefficient of maximum 3ppm/°C.

EY-A Series Balances

The EY-A series are dual-range, high-precision top-loading balances with a resolution of 1/30,000 in each range and a temperature coefficient of maximum 10ppm/°C. The balance automatically selects the higher range when the lower range has been overloaded, unless the range hold key has been previously pressed. The Range Hold function is active when its LED pilot lamp is illuminated.

Common Features of EX-A and EY-A Series

Every balance in both series is housed on a sturdy die-cast chassis and includes the following features:

• Ultra-stable weighing achieved by rounding the extra lower digit and filtering.
• Convenient optional interfaces: IEEE-488, RS-232C, parallel BCD, and 20mA current loop.
• Taring capability up to the maximum capacity of the balance, activated by a button press or external terminals. Taring is typically used to cancel the weight of a container.
• Easy-to-read cobalt blue display.
• Clear visual annunciators for various functions.
• Print key for commanding a print of weighing data when an output option and printer are connected.

Please read this manual carefully before you start to use your new balance!

Installation

1. Unpacking

A screwdriver and fuse are attached to the top of the packing material. The weighing pan and its support are wrapped in plastic and located to the side of the packing material.

1. Lift the upper packing material and remove the screwdriver and fuse.
2. Take out the instruction manual, protective cover, pan, and its support.
3. Take out the main unit and remove the protective plastic.

Figure 1: Diagram showing the unpacking process of the balance, illustrating the removal of packing materials and components.

2. Power Main Voltage

The power main voltage for each unit is factory preset at 100, 115, 220, or 240 V AC and cannot be adjusted by the user. The factory preset voltage is clearly marked on the rear of the case, just above the power cable entry point.

• Fuse: 0.5A for 100/115V & 0.2A for 220/240V.
• The balance can operate on a power frequency of either 50 or 60 Hz.

Figure 2: Diagram illustrating the rear of the balance, highlighting the fuse holder and voltage marking.

3. Opening the Case

Before opening the case, it is advisable to check the initial dip-switch settings on page 5, paragraph -5, to determine if opening the case is necessary for changes.

1. Remove the weighing pan and its support if they are already installed.
2. Unscrew the single large screw that holds the upper and lower cases together.
3. Lift up the upper case.

Figure 3: Diagram showing the process of opening the balance case, including removing the pan and unscrewing the main screw.

4. DIP-Switch Programming

The dip-switches are located on the lower right side of the display board and are used to program parameters for averaging time, display rate, and no-motion band.

-1 Averaging Time (Segment No. 1 & 2)

Data displayed is the average of all past data measured within the programmed averaging time. The following table indicates the settings for various averaging times.

Figure 4: Diagram showing the location of the dip-switches on the display board.

-2 Display Rate (Segment No. 3)

The display rate defines the time interval between each display update. A faster display rate is suitable for filling applications where weight changes rapidly. A slower display rate is suitable for stable weighing. The table below indicates the settings for various display rates.

-3 Segments 5 & 6

Segments 5 & 6 are used internally and should not be changed (OFF/OFF).

-4 No-motion Band (Segment No. 7 & 8)

The No-motion band is the allowed range of weight deviation/oscillation. When weight deviation is within the programmed range, the no-motion annunciator will illuminate. The no-motion band can be programmed by setting the segments as shown in the following table.

* "d" means divisions or scale interval. "±1d" means ± 1 mg for EX-300A.

-5 Dip-switch Settings

The dip-switches are set, at the time of shipment, as follows:

* ON when Option-09 fitted

5. Closing the Case

(Refer to Figure 3.)

1. Replace the upper case on the lower case.
2. Replace the large screw.

6. Installation Site

1. Avoid installing the balance in direct sunlight.
2. The balance should be operated in normal room temperature and other environmental conditions. Optimum weighing conditions are around 20°C (or 68°F) with a relative humidity level of about 50-60%.
3. The balance should be used on a stable base, free from excessive vibration.
4. The weighing room should be kept clean and should not be prone to excessive air movement. The balance must be level.

Figure 5: Diagram illustrating ideal installation conditions, showing a balance on a stable surface, avoiding direct sunlight and air currents.

7. Leveling the Balance

After placing the balance on an appropriately solid surface, level the balance using the adjustable front feet and the level vial located under the pan support. Rotate the front feet of the balance until the bubble in the vial is centered within the red circle.

Figure 6: Diagram showing the balance with its adjustable feet and a level vial, indicating the leveling process.

8. Installation of the Protective Cover

• Remove the dust ring by unscrewing all the screws.
• Place the protective cover on tightly without wrinkling.
• Replace the dust ring using the three screws.
• Replace the pan support and weighing pan.

Panel Description

The following list describes the components and indicators on the balance panel:

• (1) Polarity annunciator
• (2) No-motion annunciator
• (3) Weight display
• (4) Tare key
• (5) Model marking
• (6) Print key
• (7) Adjustable front feet
• (8) Rear foot
• (9) Weighing pan
• (10) Plastic cover for span volume
• (11) Slot for optional interface
• (12) Fuse holder
• (13) Power cable
• (14) Power main voltage marking
• (15) Ground Terminal
• (16) External tare terminal
• (17) Mode switch
• (18) Power switch
• (19) Range hold key (EY only)
• (20) Power pilot lamp (LED)

Figure 7: Front view diagram of the balance, with numbered callouts pointing to various panel components like the display, keys, and pan.

Figure 8: Side view diagram of the balance, showing the location of the fuse holder and other external features.

Figure 9: Rear view diagram of the balance, indicating the power cable, ground terminal, and interface slot.

Calibration

Calibration of the balance is required upon initial installation, when changing the installation site, and approximately every three months thereafter.

Weight is defined as Mass × acceleration due to Earth gravity (approximately 9.8m/s² in a vacuum). However, gravity, air buoyancy, and various other factors vary by location and over time.

1. Preparation

1. Check that the balance is horizontal.
2. Turn on power and allow a warm-up period of at least 30 minutes.
3. Obtain a standard weight equal to the maximum capacity of the balance.

2. Procedure

1. Remove the plastic span protection plug from the rear of the balance.
2. Inside, a small volume screw is accessible with a small screwdriver (such as the one supplied with the balance).
3. Confirm that nothing is on the pan and press TARE. The weight display must show zero and be stable.
4. Place the standard weight on the pan.
5. If the display does not indicate the correct weight, turn the span screw clockwise if the display is too low, and anticlockwise if it is too high.
6. Remove the standard weight, and if the display does not zero, press TARE (zero and span are slightly interactive).
7. Repeat the above steps until a stable zero and exact weight display are obtained.

Operation

1. Weighing

1. Press TARE to zero the display.
2. Place the object(s) to be weighed on the pan.
3. Read the displayed weight after the display is stable (when 'O' is displayed).

2. Weighing-In

1. Place a container on the pan.
2. Press TARE to zero the display or use a remote N/O switch connected to the rear TARE input terminals.
3. Fill the container until the target weight is reached.
4. When mixing ingredients in a container, press TARE after each addition.

3. Weighing-Out

1. Place a full container on the pan.
2. Press TARE to zero the display.
3. When anything is subsequently removed from the container, the amount removed will be displayed as weight loss.

4. Weighing a Deviation

1. Place a reference or standard sample weight on the pan.
2. Press TARE and then remove the weight; weight loss will be displayed.
3. Now, any sample weight (to be compared with the reference weight) placed on the pan will indicate its deviation from the reference (zero display) as a positive or negative display. This function is useful in check-weighing operations.

Options

This section covers Breeze-Breaks, Under-hooks, and Interfaces.

• 1. OP-01: Parallel BCD output.
• 2. OP-02: Plastic Breeze-Break (EX-300A/EY-320A only).
• 3. OP-03: RS-232C serial interface.
• 4. OP-04: Glass Breeze-Break (EX-300A/EY-320A only).
• 5. OP-05: Under-hook (EX-300A/EY-320A only).
• 6. OP-06: Under-hook (EX-3000A/EY-3200A only).
• 7. OP-09: GP-IB IEEE-488 interface.

1. Breeze-Break

Two types of breeze-breaks are available for the EX-300A/EY-320A balances:

• OP-02: A simple unfolding plastic box-type structure with a flip-up lid. When placed around the pan, it excludes light drafts.
• OP-04: A taller, more solid glass and metal structure with opening sides (glass) and top (metal). This type is installed by removing the pan & pan support, placing the breeze-break on top of the balance, and then replacing the pan & pan support inside the breeze-break.

Figure 10: Diagram of the OP-02 plastic breeze-break, showing its unfolded box-like structure.

Figure 11: Diagram of the OP-04 glass breeze-break, showing its more enclosed structure.

Figure 12: Diagram of the balance with a breeze-break installed, illustrating how it encloses the weighing pan.

2. Under-Hook

An under-hook is required for weighing suspended objects. One application is determining the floating weight of an object when suspended in a liquid. The relative density (specific gravity) of an object is found by the ratio of its mass to the mass of an equal volume of pure water at maximum density (4°C). 1 litre = 1kg [1 litre-1-000028dm³ std.a.p. of 1-01325 × 10⁵ N/m²]. An object immersed in a fluid will experience a loss in weight (tare before immersion) equal to the weight of the fluid it displaces.

Please recalibrate the balance for weighing in suspension.

OP-05 is designed for EX-300A/EY-320A, and OP-06 for EX-3000A/EY-3200A.

Installation Method

1. Remove the pan and pan support and carefully tip the balance upside-down.
2. Remove the small metal cover found underneath the balance directly below the brass weighing pan peg.
3. Gently screw the under-hook into the threaded hole in the center of the brass bolt now accessible.
4. Turn the balance the right way up and place it on a solid table with a hole cut in it through which the under-hook can freely protrude.
5. Replace the pan & pan support, install the suspension harness, and recalibrate the balance.

Figure 13: Diagram showing the underside of the balance with the metal cover removed, revealing the threaded hole for the under-hook (OP-05/OP-06).

Figure 14: Diagram illustrating an object suspended from the under-hook for weighing in a liquid.

3. Interfaces

OP-01, OP-03, and OP-09 interfaces occupy the same space in the balance; therefore, only one may be installed at a time.

1. Option-01: Parallel BCD Output

Option-01 is a parallel BCD (binary-coded-decimal) output card for interfacing the balance to peripherals with BCD input capability. An A & D printer AD-8114B can be used with this option. The rear panel MODE switch should be OFF for Balance Keyboard Print Control & ON for Automatic Single Print when Stable.

BCD Output Table

TTL level, positive logic, fan out 3.

Mating connector: AMPHENOL: 57-30500

Print command: Positive pulse with 1m. sec. width. Pin 49.

No polarity: "Lo" when the display is zero, -P or being Tared.

Busy: Fan in 1, latches output data when input is low.

Figure of OP-01 connector: A circular connector with 25 pins, labeled 25 and 26, indicating the pin layout for the BCD output.

2. Option-03: Serial RS-232C Interface

Option-03 is a serial RS-232C interface card for interfacing A & D balances to an AD-8116 compact printer or another external device such as a computer.

a) Specifications

• Type: EIA-RS-232C, Passive 20mA Current Loop
• Method: Half-duplex method, asynchronous transmission
• Format: Baud rate: 600 or 2400 (dip-switch selectable)
• Data bit: 7
• Parity bit: 1 (EVEN)
• Stop bit: 1
• Code: ASCII

Figure illustrating RS-232C data format: A waveform showing START BIT, DATA BITS (LSB to MSB), PARITY BIT, and STOP BIT. RS-232C voltage levels: 1 = -5V to -15V, 0 = +5V to +15V. 20mA Current Loop levels: 1 = 20mA, 0 = 0mA.

b) Transmission Modes

Two transmission modes are available: "Synchronised to External Command" (SECOM) Mode and "Stream Mode" (STREAM). "Balance Keyboard Output Control" (BAKOC) is available when the balance is in STREAM Mode.

• In SECOM, data is sent only after the display is stable ('O' is displayed) and after an external "READ" command is received by the balance. SECOM is only available from RS-232C.
• In BAKOC, no external command is required, and data is sent whenever the print key is pressed. BAKOC is available from both the RS-232C and Current Loop in continuous output STREAM Mode. The CURRENT LOOP is PASSIVE, requiring an external 20mA source.

c) Dip-Switch Selection

Mode and baud rate are selected by dip-switch 1 & 2 on the interface card.

Figure showing dip-switch settings for RS-232C interface: A diagram of a 3-position dip-switch.

• ON --- 2400 baud
• OFF--- 600 baud
• ON --- STREAM Mode
• OFF--- SECOM Mode

d) SECOM Mode

i) TARE Command: RxD---- (TARE) <CR> <LF>

When this TARE command is received, the TARE function of the balance is activated. As 1 second is required to execute this command, the next command should be sent no sooner than 1 second after the TARE command has been given (if sent sooner, it will be ignored).

ii) READ Command: RxD---- (READ) <CR> <LF>

When this READ command is received, a weight data sample immediately following the command will be transmitted.

Figure: Data Format for SECOM Mode. A block diagram showing HEADER, DATA, and TERMINATOR (CR LF).

Three types of HEADER are transmitted:

• OL---------- Overload
• ST---------- Stable Weight (O is on)
• US---------- Unstable Weight

Weight data samples are transmitted by ASCII numerals including the following codes:

• 2D (HEX) --- "-" (minus)
• 2B (HEX) --- "+" (plus)
• 20 (HEX) --- " " (space)
• 45 (HEX) --- "E" (exponent)
• 2E (HEX) --- "." (decimal point)

Keep the MODE switch located on the rear panel of the balance OFF whenever SECOM is in use and segment number 4 of the balance (not Option-03) dip-switches is set OFF (the initial setting). This format will be Keyboard Print Control after READ command received. Balance segment number 4 must be ON for normal SECOM format when printing will be controlled externally via READing.

e) STREAM Mode

In this mode, data is transmitted continuously without need of a data request.

Figure: Data Format for STREAM Mode. A block diagram showing HEADER, SPACES (7), WEIGHT DATA (9), UNIT, and TERMINATOR (CR LF).

• HEADER: NULL: 00 (HEX) - Display is stable.
• HEADER: DC2 : 12 (HEX) - Display is unstable.
• " " - SPACE - 20 (HEX)

f) Rear Panel MODE Switch plus balance dip-switch #4 and Automatic Printing.

For the Automatic sending of one print command per weighing event in STREAM mode when the display is stable, the MODE switch should be ON with #4 OFF. A weighing event is judged to be over when the display has returned to within zero ±10d after the previous object has been removed. If #4 is ON, a print command will be sent once every display cycle (continuously) and the setting of the rear panel MODE switch will have no effect.

g) Passive 20mA Current Loop Pin Connections:

Figure: 7 Pin DIN connector diagram.

h) Circuit Diagram

Figure: Circuit diagram for RS-232C and Current Loop connections, showing RXD, TXD, RTS, CTS, SG, and current loop paths with +5V.

i) RS-232C Pin Connections: AD-8116 and other devices.

AD-8116 uses a KO:256 interface cable. Select Stream Mode at 2400 baud. These balances are designated as Data Communication Equipment for other devices.

Figure: Diagram of a 25-pin D-sub connector with pin assignments for RS-232C communication.

j) Standard Accessory

Current loop connector (1) TCP 0576

* An RS-232C connector is not provided with this option because A & D peripherals such as AD-8116 are equipped with cables and connectors.

k) Sample RS-232C Computer Program

When interfacing to NEC PC-9801 (Microsoft BASIC), in 'SECOM' mode, type in the following:

• "M" "O" "N" "CR"
• "S" "S" "W" "2" "CR"
• "9" "4" "CR" (600 baud) "0" "6" "CR" (2400 baud)
• "CTRL" "B"

10 T$="TARE"

20 R$="READ"

30 OPEN "COM:E71NN" AS #1 *(Interface file, Even/7bits/1stop)

40 PRINT #1, "CLEAR" (CLEAR interface buffer)

50 FOR I=1 TO 100: NEXT I (Delay)

60 PRINT #1, T$ (TARE)

70 FOR I = 1 TO 2000: NEXT I (Delay after TARE)

80 PRINT #1, R$ (READ)

90 INPUT #1, HD$, DT (Receive Data)

100 PRINT HD$, DT (Display Data)

110 FOR J = 1 TO 100: NEXT J *2 (Delay after (CR))

120 GOTO 80 (Loop)

130 CLOSE #1 (Close interface file)

140 END (HALT)

*¹ "NN" is NEC Microsoft dialect & *² PC-9801 requires this delay.

3. Option-09: GP-IB General-Purpose Interface Bus (IEEE-488)

Option-09 is an interface for a controller. When selected, measured data can be transmitted to, and "TARE" commands can be received from, a controller.

(1) Specifications (Inst. of Electrical & Electronics Engineers/International Electrotechnical Commission)

All specifications comply with IEEE-488-1975 and IEC-TC66 (CO) 22.

Interface functions: SH1, AH1, T6, L4, SR1, RLO, PPO, DCO, DT1, CO.

(2) Address and Delimiter Switches

The dip switches for the address and delimiter are located on the option PCB.

Figure: Diagram of dip-switches for GP-IB address and delimiter settings.

(3) Commands

The following commands are available:

(4) SRQ (Service Request)

SRQ will not be sent out until S1 has been received after power on. When one of the following conditions has been satisfied after receiving S1, SRQ will be sent out.

• Condition 1: When data is accepted by the interface after E has been received.
• Condition 2: When an undefined code is received.

(5) Status Byte

When SRQ is ready as a result of an S1 command, the status of MSB1 becomes 1, and after the status byte is read, MSB1 becomes 0.

When SRQ is ready as a result of an undefined code, LSB1 becomes 1, and after being designated as a listener, LSB1 becomes 0.

When SRQ is ready as a result of storing data, LSB2 becomes 1, and after being designated as talker, LSB2 becomes 0.

Figure: Status Byte structure. A diagram showing MSB (7,6), MSB1 (5,4), LSB2 (3,2), LSB1 (1), LSB (0) bits, and their relation to Condition 1 (SRQ ready from undefined code) and Condition 2 (SRQ ready from storing data).

(6) Data Format

Figure: Data Format for Measured Data. A block diagram showing HEADER, MEASURED DATA (7 digit numerals), and DELIMITER (Exponent).

(7) Acquiring Measured Data

When "E" is received, the balance stores the data just measured and will transmit this data as soon as it is designated as talker. The balance should receive "E" just before being designated as talker so that the data is fresh. If "E" is received after "S1" has been accepted, the balance will store the current data and then transmit "SRQ".

N.B. The balance print key will not transmit or store data. Segment number 4 of the balance dip-switches must be ON when Option-09 is fitted.

(8) Computer Program Example (GP-IB IEEE-488)

When interfaced with HP-85, program the addresses and delimiters of each machine as below:

(a) Initialize

• 10 RESET 7 --- Interface clear
• 15 CONTROL 7, 16;130 --- Set delimiter of HP-85 as CR+LF+EOI

(b) TARE the balance

• 10 OUTPUT 701 ; "TARE"

(c) Acquire data and display

• 20 OUTPUT 701; "E"
• 30 ENTER 701; A$ DISP A$ --- Receive data into A$ and display
• 40 GOTO 20

(d) Acquire data using SRQ.

• 10 ON INTR 7 GOSUB 100
• 15 CONTROL 7, 16; 130 --- Not required with (a) 15 above.
• 20 ENABLE INTR 7;8 --- Allow SRQ from balance
• 30 OUTPUT 701; "S1" --- Allow balance to transmit SRQ
• 40 F=1
• 50 IF F=1 THEN OUTPUT 701; "E" @ F=0 -- (Instruct balance to acquire data)
• 60 GOTO 50 --- Loop
• 100 S-SPOLL (701) --- Read Status Byte from address No. 1
• 110 DISP S --- Display Status Byte
• 120 STATUS 7,1; Z --- Read Status Register
• 130 ENTER 701; A$ --- Read measured data into A$
• 140 DISP A$ --- Display measured data
• 150 F=1
• 160 ENABLE INTR 7;8 @ RETURN -- Allow SRQ from balance and return

Printers

1. Digital Printer AD-8114B

This printer interfaces with A & D balances via a BCD output interface card and a KO:145 interface cable; use Input A of the printer. The internal switches of the printer should be programmed as follows:

* Manual Print (Balance Keyboard Print Control)

• Balance MODE switch should be OFF.
• MAN/EXT switch of printer should be on EXT.
• Pressing the Balance PRINT switch will initiate printing.

* Auto Print (Automatic Single Print when Stable)

• Balance MODE switch should be ON.
• MAN/EXT switch of printer should be on EXT.
• Printing will be Automatically initiated when the object being weighed renders a stable (not-in-motion) weight display.

2. Compact Printer AD-8116

Uses a KO:256 interface cable between the printer & RS-232C interface card. The dip-switches on the RS-232C interface card inside the balance should be set to one & two ON (STREAM mode at 2400baud).

* For more detailed explanations, please see the printer manuals.