The tM-SG4 is an optional module that is used to improve the communication of RS-485 network. It provides switch selectable pull-high and pull-low resistors on RS-485 network. It also has 15-step switch selectable termination resistor such that the user can select a proper termination resistor to be connected to the RS-485 network easily. If the RS-485 network is not over 100 meters, the termination resistors are not needed. Otherwise, it may be necessary to insert two termination resistors at both end of the RS-485 network. It is not easy to calculate the value of a termination resistor on the RS-485 network. The best way to do this is to use an oscilloscope to check the RS-485 signal directly. If the impedance match of RS-485 network is OK, the oscilloscope will show a very nice square wave. If these square wave signals are distorted, the user will need to insert two termination resistors at both end of the RS-485 network.
| RS-485 Interface |
| Pull-high/Pull-low Resistance |
1 kΩ, 10 kΩ, 100 kΩ, Switch-selectable |
| Termination Resistance |
15 Steps, 65 ~ 560 Ω |
| LED Indicators |
| Power |
1 Red LED as Power Indicator |
| Termination Resistor |
1 Green LED as Termination Indicator |
| EMS Protection |
| ESD (IEC 61000-4-2) |
±4 kV Contact for Each Terminal |
| Power Requirements |
| Reverse Polarity Protection |
Yes |
| Powered from Terminal Block |
Yes, 10 ~ 30 VDC |
| Consumption |
0.5 W Max. |
| Mechanical |
| Dimensions (W x L x H) |
52 mm x 87 mm x 27 mm |
| Installation |
DIN-Rail Mounting |
| Environment |
| Operating Temperature |
-25 ~ +75 °C |
| Storage Temperature |
-40 ~ +85 °C |
| Humidity |
10 ~ 90% RH, Non-condensing |
| Termination Resistance Settings
|
| 120R |
330R |
470R |
560R |
Termination Resistance (Ω) |
| ON |
ON |
ON |
ON |
65 |
| ON |
ON |
ON |
OFF |
74 |
| ON |
ON |
OFF |
ON |
76 |
| ON |
OFF |
ON |
ON |
81 |
| ON |
OFF |
OFF |
ON |
99 |
| ON |
OFF |
ON |
OFF |
96 |
| ON |
ON |
OFF |
OFF |
88 |
| ON |
OFF |
OFF |
OFF |
120 |
| OFF |
OFF |
ON |
ON |
144 |
| OFF |
ON |
ON |
OFF |
193 |
| OFF |
ON |
OFF |
ON |
207 |
| OFF |
ON |
OFF |
OFF |
330 |
| OFF |
OFF |
ON |
ON |
256 |
| OFF |
OFF |
ON |
OFF |
470 |
| OFF |
OFF |
OFF |
ON |
560 |
|
|
| Pull-high and Pull-low Settings |
| 1k |
10k |
100k |
RS-485 Data Line Status |
| OFF |
OFF |
OFF |
No pull-high/pull-low on RS-485 data line |
| ON |
OFF |
OFF |
1k [ pull-high and pull-low |
| OFF |
ON |
OFF |
10k [ pull-high and pull-low |
| OFF |
OFF |
ON |
100k [ pull-high and pull-low |
|
| |
|
Termination Resistance On/Off Switch
|
| OFF |
Termination Resistor do NOT work. |
| ON |
Termination Resistor is worked, and TR LED is light. |
|
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