GP477R Engineering Installation

GP477R Touch Screen Installation and Interface Configuration Guide

In the process of renovating old production lines or repairing equipment, engineers often need to face human-machine interface (HMI) models from ten years ago or even earlier. The Pro face GP477R series (such as GP477R-EG11) is one of the classic 10 inch touch screens, widely used in industries such as packaging, printing, and machine tools. This model adopts AC100V power supply, provides RS-232C/422 dual standard serial communication, and is equipped with independent printer interface and AUX auxiliary input/output, which can reliably interact with various PLCs and external devices. However, due to the age, it is difficult to obtain the original factory paper manual. Improper handling of wiring and installation details can result in communication abnormalities, touch failures, and even equipment damage or electric shock accidents. Based on the original technical data of this model, this article systematically reviews the entire process of GP477R from unboxing inspection, hole fixing, power grounding to pin definition and anti-interference measures of various communication ports, aiming to provide a highly operational reference document for on-site engineers.

Open box inspection and confirmation of selected accessories

1.1 Standard Packaging Content

After unpacking, the first thing to check is whether the following items are complete:

One GP477R host

Install 4 fasteners (installation clips)

Sealing gasket (pre installed in the grooves around the body)

Quick User Guide (Single Page)

If any missing or damaged items are found during transportation, the local agent should be contacted immediately. It should be noted that this model of host does not include any communication cables, programming software, and installation tools, which need to be purchased separately.

1.2 Common optional accessories

User Manual: GP477R/577R Series User Manual, providing detailed instructions on screen editing and system settings.

Programming cable: A serial download cable (usually an RS-232C crossover cable) used to connect a PC to a GP.

Screen editing software: Pro face GP-PRO/PBIII or earlier GP Editor, depending on the operating system version.

Adapter: If a non-standard interface PLC needs to be connected, a dedicated conversion adapter may be required.

The most common difficulty encountered by on-site engineers when replacing old equipment is the loss or damage of the original cables. Therefore, it is recommended to make a self-made communication line according to the pin definition in Section 3 in advance.

Mechanical installation and waterproofing measures

2.1 Inspection of sealing gaskets

The GP477R is designed with a frontal protection level of IP65 (when correctly installed on the control cabinet panel), and its key component is the rubber sealing gasket installed in the groove around the display screen. Before installation, the host display screen must be placed facing down on a flat surface, and the gasket must be carefully checked for complete insertion into the slot, no distortion or damage. If the gasket falls off or ages and cracks, the subsequent waterproof effect will be completely lost, and the gasket of the same specification must be replaced.

2.2 Panel Hole Size

According to the external dimension diagram in the manual (page 3 of this document), the installation opening of GP477R-EG11 is rectangular, and the specific dimensions need to be obtained from the original mechanical drawing. It is generally recommended to cut the control cabinet panel according to the following general rules:

The edge of the opening must be flat and free of burrs. It is recommended to use laser or wire cutting for processing.

The opening size should be slightly larger than the GP rear shell, but it must be ensured that the sealing ring can be fully compressed. The recommended standard opening tolerance is+0.5/-0mm.

The thickness of the panel material should be between 1.5mm and 5mm to ensure effective clamping of the fasteners.

2.3 Fixed method

Insert GP477R into the opening from the front (outer side) of the panel, ensuring that the sealing rings around it evenly contact the surface of the panel.

Turn inside the control cabinet and insert the four installation fasteners into the slots on the side of the main body casing.

Tighten the screws on the fasteners in sequence. When tightening, use a diagonal sequence and gradually apply torque.

Key parameter: The tightening torque must be controlled within 0.5-0.6 N · m. Exceeding this torque may cause the plastic shell to break or the sealing ring to deform excessively and fail. If there is no torque screwdriver, you can use a regular screwdriver to tighten until you feel obvious resistance, and do not continue to apply force.

After fixing, check from the front whether the display screen is level and the sealing ring should show a uniform indentation.

Power wiring and grounding

3.1 Power specifications and hazard warnings

The power terminal of GP477R-EG11 is located on the back of the host and only accepts AC100V (± 10%) input. This is the most common mistake of this model: if AC220V or DC24V is mistakenly connected, the power board will immediately burn out and cannot be repaired. In addition, there is no power switch inside the machine, so a circuit breaker that complies with local electrical regulations (recommended rated current 2A, C-type trip curve) must be installed in the control cabinet as a disconnecting device.

3.2 Wiring steps for power terminals

Power off confirmation: Before connecting any wires, make sure that the power cord is completely disconnected from the power supply network and the circuit breaker is in the OFF position.

Open the terminal cover: Use a Phillips screwdriver to unscrew the protective cover on the power input terminal block.

Terminal definition: The terminal block has three markings:

L: AC100V live line

N: AC100V neutral wire

FG: Grounding terminal (connected to GP casing)

Use circular terminals with insulated sleeves: To prevent short circuits caused by loose screws, it is recommended to use JST V2-MS3 or equivalent circular cold pressed terminals with insulated sleeves. The maximum cross-sectional area of the wire is 2mm ² (approximately 14AWG).

Wiring: Loosen the corresponding screw, insert the wire with the pressed terminal and tighten it again, with a torque of 0.5-0.6 N · m.

Grounding: The FG terminal must be directly connected to the grounding copper bar of the control cabinet using a separate wire, and the grounding resistance should be less than 100 Ω. It is prohibited to short-circuit FG and N lines, nor to suspend them, otherwise the anti-interference ability of GP will sharply decrease.

3.3 Anti interference measures for power supply

It is recommended to parallel a surge absorber (varistor) at the power input end to suppress spikes caused by lightning strikes or inductive load switching.

If the factory power grid has severe noise (such as a large number of frequency converters), an isolation transformer or noise filtering transformer should be installed at the front end of the GP power supply.

The power cord should be as short as possible and routed separately from the power and motor lines to avoid bundling in the same cable tray.

Twisting the power cord into a twisted pair before connecting it to the terminal can further improve the common mode noise suppression capability.

Serial interface (RS-232C/RS-422)

The GP477R is equipped with a 25 pin D-sub female socket (located on the back of the body) that can be configured in RS-232C or RS-422 mode for connecting PLCs, computers, or other master station equipment. This interface supports full duplex communication, with a maximum baud rate typically reaching 115.2kbps (depending on the system program version).

4.1 Pin Allocation Table

Pin signal name description Pin signal name description

1 FG frame grounding 14 VCC+5V ± 5% output 0.25A

2 SD sends data (RS-232C) 15 SDB sends data B (RS-422)

3 RD receives data (RS-232C) 16 RDB receives data B (RS-422)

4 RS request sent (RS-232C) 17 NC not connected

5 CS clear send (RS-232C) 18 CSB clear send B (RS-422)

6 NC-19 ERB allows reception of B (RS-422)

7 SG signal grounded 20 ER allows reception (RS-232C)

8 CD Carrier Detection (RS-232C) 21 CSA Clear Transmission A (RS-422)

9 TRMX terminal resistor (RS-422) 22 ERA allows receiving A (RS-422)

10 RDA Received Data A (RS-422) 23 Reserved

11 SDA sends data A (RS-422) 24 NC not connected

12 NC-25 Reserved

13 NC - 

Important precautions:

Pin 14 (VCC) can output a+5V/0.25A power supply to external converters or low-power devices. This output has no overload protection, and it must be ensured that the total current does not exceed the rated value during use, otherwise it will damage the internal power circuit of the GP.

In RS-422 mode, pin 9 (TRMX) is required to connect the terminal resistor. When GP is located at the end of the bus, TRMX should be short circuited to RDA (pin 10); The specific short-circuit method depends on the communication protocol, and it is generally recommended to connect only the two end devices to a 120 Ω resistor when connecting multiple points.

The signal ground (pin 7 SG) must be connected to the signal ground of the opposite device, otherwise it may cause common mode voltage damage to the interface chip.

4.2 Recommended connectors and cables

Connector: OMRON XM2A-501 (25 pin male) with threaded locking.

Shell: OMRON XM2S-2511, with matching screws of M2.6 × 0.45 coarse teeth.

Cable: Hitachi cable CO-MA-VV-SB5P × 28AWG or other twisted pair shielded cable (at least 5 pairs of wires) is recommended. RS-232C can use standard direct serial cable, while RS-422 requires twisted pair transmission of differential signals.

4.3 Typical Wiring Examples

RS-232C three wire system (communicating with PC serial port): GP's SD (2) → PC's RD, GP's RD (3) → PC's SD, GP's SG (7) → PC's SG. If hardware handshake is required, GP's RS (4) and CS (5) can be connected to the corresponding signal of the PC, but most applications only require three wires.

RS-422 four wire system (communicating with PLC): SDA of GP (11) → RDA of PLC, SDB of GP (15) → RDB of PLC, RDA of GP (10) → SDA of PLC, RDB of GP (16) → SDB of PLC, while connecting SG (7) of GP to SG of PLC.

Printer interface

The GP477R also has a 14 pin flat interface on the back (Centronics compatible) for connecting to parallel printers to print alarm records or hard copy screens. The interface adopts Fujitsu FCN-787P014-G/R connector.

Pin Function Summary (Based on Original Document Inference):

Standard parallel port signals such as data cable STB, D0-D7, BUSY, etc.

Attention: The 12th and 13th pins are idle and must not be connected to any wires, otherwise it may damage the printer interface.

In practical engineering, due to the fact that modern printers are mostly USB or network interfaces, the frequency of use of this port is extremely low. If data recording is required, it is recommended to use a serial port external micro printer or forward the data to the upper computer through PLC.

AUX auxiliary interface (input/output)

The AUX interface is a 15 pin D-sub female socket that provides the following very practical external control and monitoring signals, which are very useful for integrating safety emergency stop circuits and equipment status indicators.

6.1 Pin List

Pin signal function description

1 TSW0 touch switch output (8-bit, TSW0~TSW7)

2 TSW1 

3 TSW2 

4 TSW3 

5 TSW4 

6 TSW5 

7 TSW6 

8 TSW7 

9 RUN mode output: ON when GP is running; OFF when standby or power is off

10 ALARM alarm output: Conducted when a fatal hardware or software error occurs

11 BUZZ buzzer output: Follow the action of GP internal buzzer

12 DC24V output common terminal (DC24V side)

13 AIN-C input common terminal (DC24V side)

14 AOUT-C output common terminal (GND)

15 RESET reset input (low pulse effective)

6.2 Main application scenarios

Touch switch output (TSW0~7): When the user presses the specified touch switch on the screen, the corresponding transistor output will turn on. It can be directly used to control external indicator lights or relays, achieving "physical devices can be operated on the screen". These outputs are in the form of open collector and require an external pull-up resistor or DC load.

RUN output: can be used to light up a "running" indicator light when GP is running, or to interlock with PLC.

ALARM output: When GP detects serious faults such as screen memory verification errors or system errors, this output will be activated, thereby cutting off the main contactor or triggering the central alarm system.

Buzzer output: It can be connected in parallel with an external high-power buzzer to synchronously drive the external speaker when the GP emits a button sound or alarm sound.

Reset input (RESET): Short circuit the RESET pin (low level active) to AIN-C to reset the GP software, which is equivalent to powering on again. GP that can be used for remote reset of crashes.

When wiring, please distinguish the common terminal: use AOUT-C (GND) for the output circuit and AIN-C (DC24V) for the input circuit. We recommend using the OMRON XM2A-1501 plug, with the same screw specifications as the serial port M2.6.

Anti interference and signal line wiring

As a touch screen, GP477R is highly susceptible to electromagnetic interference from strong electrical devices such as frequency converters and contactors, resulting in communication interruption, touch misoperation, or display flickering. The following measures must be strictly implemented:

Separation of signal lines and power lines: All I/O signal lines (including serial ports, AUX, printers) must be routed separately from AC power lines, motor lines, and inverter output lines, with a minimum spacing of 20cm. If crossing is necessary, it should be done vertically instead of parallel.

Use shielded cables: Serial and AUX cables should use cables with total shielding and twisted pair structure. The shielding layer should be grounded at a single point at the GP end (connected to the FG terminal) and suspended at the opposite end to avoid ground current.

Grounding independence: The FG terminal of GP cannot be connected in series with the ground wire of the power equipment, and must be separately led to the grounding copper bar of the control cabinet. The grounding resistance should be less than 100 Ω, and if possible, it should be less than 10 Ω.

Surge protection: Connect a varistor (such as S14K275) in parallel at the power input end, or use a socket with filtering function.

Communication line length limit: RS-232C distance ≤ 15 meters, RS-422 ≤ 1200 meters (actual affected by baud rate). When exceeding the recommended distance, please use a repeater.

Summary of Safety Operations and Maintenance Suggestions

8.1 Safety principles that must be absolutely followed

No live plugging or unplugging: Before any operation of connecting or disconnecting cables, the GP power supply must be cut off. Otherwise, it may burn the port or cause electric shock.

Unauthorized disassembly is prohibited: GP has high-voltage circuits and lithium batteries (used for clock backup) inside. If lithium batteries are replaced incorrectly, there is a risk of explosion, and users cannot replace the batteries themselves. Please contact an authorized repair station when replacement is required.

External emergency stop: Virtual buttons on the touch screen must not be used for safety emergency stop functions. An independent mechanical emergency stop switch must be installed separately, and the main circuit cannot be directly controlled through GP.

Communication fault safety design: The control system should be able to detect communication interruptions between GP and PLC (such as through heartbeat signals) and put the machine into a safe state in case of a fault, rather than blindly executing the last instruction.

8.2 Precautions for Daily Maintenance

Cleaning: Use a soft dry cloth to wipe the surface of the touch screen. Do not use paint thinner, alcohol, or organic solvents to avoid damaging the panel coating.

Environment: Avoid places with direct sunlight, excessive dust, chemical vapors, or severe vibrations. The working temperature range is usually 0-50 ° C, and the humidity is 10-90% RH (without condensation). Severe temperature changes can cause internal condensation, which may lead to short circuits.

Startup interval: If you need to power on again after shutting down, you should wait at least 5 seconds, otherwise it may cause startup failure.

Data backup: Screen display programs and recipe data should be regularly uploaded and backed up through programming software to prevent memory aging and loss.