Additional Installation Tips
When experiencing communication problems in noisy environments or when operating close to temperature limits, the following recommendations are to be noticed.
Grounding the HMI Panel
The mounting clamps of the HMI panel do not provide a secure grounding connection between the panel and the device cabinet, see 1 in drawing above. To ground the HMI panel:
Connect a wire, that is sized correctly according to local electrical codes, between the quick-connect terminal connector on the HMI panel and the chassis of the panel, see 2 in drawing above.
Connect a wire or grounding braid, that is sized correctly according to local electrical codes, between the chassis of the HMI panel and the closest grounding point on the door, see 3 in drawing above.
Connect a strong but short grounding braid between the door and the device cabinet, see 4 in drawing above.
Twist the cables onto the 24 V DC feed, see 5 in drawing above.
2 turns around the ferrite core provide 4 times the suppression of 1 turn.
3 turns around the ferrite core provide 9 times the suppression of 1 turn.
Connect a wire or grounding braid, that is sized correctly according to local electrical codes, between the chassis of the HMI panel and the closest grounding point.
Note
The grounding wires should be short and the conductor should have a large area.
A long, thin grounding wire has a very high impedance (resistance) at high frequencies and does not guide disturbances to the ground.
Multi-wire conductors are better than single wire conductors with the same area.
A braided conductor wire with the same area is even better. The best is a short, thick grounding braid.
Ethernet Connection in the HMI Panel
In some industrial units for Ethernet, the RJ45 contact’s shield is connected to the chassis via a capacitor, see 1 in drawing above.
The Ethernet shield of the HMI panel is directly connected to the chassis, see 2 in drawing above.
Check whether the other Ethernet unit has its shield directly grounded or grounded via a capacitor.
Note
In many cases, connecting the shielded Ethernet cabling to the chassis at both ends is inappropriate. Humor grounding loops can occur. Unshielded cabling may even result in fewer communication errors.
A good solution may be to use a shielded Ethernet cable, but to connect the shield at one end only.
One option is to break the shield, see 3 in drawing above.
A more elegant method is to expand the shielded Ethernet cabling with a piece of unshielded Ethernet cable, see 4 in drawing above.
The shield can be grounded via an external 0.1 μF/250 V film capacitor, see 5 in drawing above. This connects the HF transients to ground.
To Achieve Better EMC Protection
Initially, use the original cabling from Beijer Electronics primarily.
Place the 24 V DC and communications cabling in one cable trunk/cable duct and 230/380 V AC in another. If the cables need to be crossed, cross them at 90° only. Avoid combining the cabling for stronger 24 V DC outputs with the communication cabling.
Use shielded cables for RS-232 communication.
Use twisted pair and shielded cabling for RS-422 and RS-485.
Use the cabling intended for the bus type; Ethernet, Profibus, CC-Link, CAN, Device Net etc.
Install and connect according to applicable specifications for the relevant bus standard.
Use shielded cabling for Ethernet, preferably with foil and a braided shield.
D-sub covers should be shielded, and the shield should be connected to the cover 360° where the cable enters.
Connect the shield at both ends.
With longer distances, there is a risk that the ground potential may be different. In that case, the shield should only be connected at one end. A good alternative is to connect the other end of the shield to the ground via a 0.1 μF / 250 V film capacitor. Both ends are then connected to the ground in terms of HF, but only connected to the ground at one end in terms of LF, thus avoiding the 50/60 Hz grounding loops.
Use an EMC cable gland or regular plastic cable gland, remove the outer jacket and connect the shield to the installation plate with a 360° metal cable clamp.
Place the 24 V DC and communications cabling in one cable trunk/cable duct and 230/380 V AC in another. If the cables need to be crossed, cross them at 90° only. Avoid combining the cabling for stronger 24 V DC outputs with the communication cabling.
Note
Ferrite cores that are snapped onto the shielded cabling may remove minor disturbances. Large ferrite pieces that are snapped onto unshielded cabling and where the wires go 2-4 times around the cores are approximately 5-25 times more efficient.
Ambient Temperature
The maximum ambient temperature for the HMI panel is provided in the specifications. The ambient temperature refers to the temperature in the device cabinet which cools the HMI panel's electronics.
In most cases, the ambient temperature for the HMI panel is significantly higher than the device cabinet’s ambient temperature.
If the cabinet is tall and there are a number of heat-generating devices, the temperature at the top of the cabinet is considerably higher than the temperature increase that would be expected. All electronics are sensitive to heat. The lifespan of an electrolytic capacitor is cut in half with an 8-10 °C increase in temperature. A 15-20 °C temperature increase results in a quarter of the lifespan etc.
Rittal has a good program for estimating the anticipated average temperature in the cabinet as well as a large program for controlling the temperature in the device cabinet.
An enamel-coated steel cabinet has a radiant heat value of 5.5 W/m2 per °C.
Installing a fan inside the cabinet evens out the temperature, while moving air provides considerably better cooling than still air.
Install the fan so that it sits in a cooler area and blows cold air against the HMI panel. If the fan is mounted at the top and sucks warm air upwards, the ambient temperature of the fan becomes higher, resulting in a shorter lifespan.
An approximate value of the net power consumption for the HMI panel can be calculated by multiplying the supply voltage with the current drawn by the HMI panel. This is assuming that all supplied power is transformed to heat.
Note
Please ensure that the temperature will not exceed the maximum ambient operating temperature in the enclosure. This can be influenced by other heat generating devices.
Safety
If a power supply that meets safety standards is used and only powers the HMI panel, there is no problem. See 1 in drawing above.
However, if a 24 V unit that also powers other units is used, there is reason to be cautious, see 2 in drawing above. The HMI panel does not have insulation that meets safety requirements in the event of a potential short circuit between 230 V AC and 24 V DC. It is assumed that the 24 V power supply is secure, for example, SELV according to EN 60950 (protection against electric shock) and UL 950.
Note
Here is an example that explains why a secure 24 V DC power supply can be ruined by mixing 24 V relay contacts with 230 V AC relay contacts in a smaller controller. Check that the clearances and creepage distances between 24 V DC and 230 V AC fulfill EN 60950 or UL 950. If not, input a separate 24 V unit into the HMI panel.
If there is a substantial distance between the relay contacts for 24 V DC and 230 V AC, it is OK to use the same 24 V devices for all feeds. See 3 in drawing above.
Connect 0 V on the 24 V power supply to the ground, see 4 in drawing above. This offers three advantages:
Safety is increased. The 24 V power supply is not live in the event of a faulty connection or short circuit between 0 V (24 V) and 230 V phase.
Transients on the 24 V feed are connected to the ground.
No risk that the 24 V feed is at a high level in relationship to the ground. This is not unusual since there is high static electricity.
Galvanic Isolation
The HMI panel has galvanic isolation against the 24 V DC power supply but no galvanic isolation between the communication ports for RS-232, RS-422, RS-485 and USB. Only the Ethernet connection has galvanic isolation.
When a PC is connected to the HMI panel, the internal 0 V (GND) of the panel is connected to the protective ground via the PC.
A number of USB devices can have the shield connected together with the protective ground. In the image above, the 0 V (GND) of the HMI panel is connected to the protective ground when a USB memory stick, keyboard, or similar device is plugged in.
If a number of units are connected that have a 0 V and a ground connection, and these are connected to various grounding points, there is a substantial risk of problems. Grounding currents go through communication cables, the rear plate of the controller, internally in the HMI panel, and can cause errors.
Use external units to improve communication and achieve galvanic isolation. Westermo has good industry-standard insulators that are also insulated from the 24 V DC feed.
Note
It is very important to make sure that the 24 V feed in the external insulation unit is not connected to one of the communication outlets. If it does not have 100% insulation against the 24 V feed, disturbances and grounding currents from the 0 V on the 24 V side disrupt the communication.
Using this type of unit solves one problem but creates a larger problem! A substandard installation may work now, but problems may arise when other devices are connected.
CAN Interface
Cable Recommendations
Use shielded, twisted pair cable to improve noise immunity and to reduce radiated emissions.
Characteristic impedance: 120 Ohm (typical)
Propagation delay: 5 ns/m
Mutual capacitance: 40 pF/m (typical, wire to wire)
Recommended cable cross section:
Bus length 0-40 m: 0.25-0.34 mm² (AWG23,AWG22), 70 mOhm/m
Bus length 40-300 m: 0.34-0.6 mm² (AWG22,AWG20), < 60 mOhm/m
Bus length 300-600 m: 0.5-0.6 mm² (AWG20), < 40 mOhm/m
Bus length 600-1000 m: 0.75-0.8 mm² (AWG18), < 26 mOhm/m
GND should be included in the cabling to provide a reliable reference Ground for each CAN node (potential equalization). Use two wire pairs; one pair for communication and one pair for GND. Do not use the cable shield to connect GND.
Termination
To achieve the best signal integrity, noise immunity and reliable bus performance, the CAN network must be terminated at its two most distant CAN nodes with 118Ohm... 130Ohm resistors. The recommended resistor value is 120 Ohm/1%/0.25W on each end.
Place the termination resistor near the CAN bus connector (as close as possible).
This product has no integrated termination resistors. They must be added externally.
Restrictions and Recommendations
The maximum supported bit rate depends on bus load, bus topology, number of nodes, bus termination, propagation delay of each CAN node and the bus length.
Do not connect more than 32 nodes to one CAN network without using a repeater.
If the bus length exceeds about 200 m, it is recommended to use CAN nodes with built-in galvanic isolation.
If the bus length exceeds 1000 m, a CAN bus repeater should be used.
For additional information refer to the driver documentation for FreeCAN and Can Open in the iX Developer software.
Cable and Bus Termination RS-485
If maximum transfer distance and maximum transfer speed is needed, shielded and twisted pair cable should be used. The mutual capacitance may not exceed 52.5 pF/m, and the cable area should be at least 0.25 mm2 (AWG 24).
0 V, the reference voltage for communication should be included in the cabling. With two-way communication use two pairs; one pair for communication and one pair for 0 V.
The shield must be grounded at one end. The other end is usually grounded, but with longer distances or when there is a difference in the ground potential, the shield should be connected to the ground via 0.1 μF / 250 V film capacitor to prevent ground current in the braided shield. Some manufacturers recommend that the shield be grounded at each node. Various manufacturers have different systems for bus termination.
Depending on the recipients’ design, the bus wires may be on the same level or require pull-up or pull-down to ensure that no faulty signals are detected when the bus is in resting mode (all transmitters are disconnected).
USB Flash Drive
The USB port, or ports, are of 2.0 standard and support FAT16, FAT32 and exFAT file systems for USB flash drives (option, sold separately).
FAT16: up to 2 GB
FAT32: up to 32 GB
exFAT: up to 2 TB
Image Sticking
When utilizing TFT LCD HMI panels in applications where a fixed or partially fixed image remains displayed on the screen for extended periods of time, users may experience a phenomenon referred to by the LCD industry as Image Sticking. Image sticking, sometimes also called “image retention” or “ghosting", is a phenomenon where a faint outline of a previously displayed image remains visible on the screen when the image is changed.
Image sticking can be caused by:
Static images
No screensaver
Sharp contrast transition (e.g. black/white)
High ambient temperatures
How Image sticking can be avoided or reduced:
Use the screensaver functionality (see SW manual).
Changing constantly between static and dynamic images.
Avoid excessive brightness differences between foreground and background elements.
Use colors with similar brightness.
Use complementary colors in follow-up images.