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RS-422 drivers, receivers are unidirectional. RS-485 driver, receivers are set so that the drive can tri-state and be in parallel with the receive lines. You can think of it like RS-485 IC can set as driver or receiver by input pin pulled high or low while RS-422 IC’s are either drivers or receivers only.
In general the industry considers RS-422 to/from RS-485 to be 100% compatible with no issues. So, in general any encoder using RS-422 compatible drivers works with any Kollmorgen drive encoder input.
| Specifications | RS232 | RS423 | RS422 | RS485 | |
|---|---|---|---|---|---|
| Mode of Operation | Single-Ended | Single-Ended | Differential | Differential | |
| Total Number of Drivers and Receivers on One Line (One driver active at a time for RS485 networks) |
1 Driver 1 Receiver |
1 Driver 10 Receiver |
1 Driver 10 Receiver |
32 Driver 32 Receiver |
|
| Maximum Cable Length | 50 ft. | 4000 ft. | 4000 ft. | 4000 ft. | |
| Maximum Data Rate (40 ft. - 4000 ft. for RS422/RS485) | 20 kb/s | 100 kb/s | 10 Mb/s - 100 kb/s | 10 Mb/s - 100 kb/s | |
| Maximum Driver Output Voltage | +/-25V | +/-6V | -0.25V to +6V | -7V to +12V | |
| Driver Output Signal Level (Loaded Min. | Loaded | +/-5V to +/-15V | +/-3.6V | +/-2.0V | +/-1.5V |
| Driver Output Signal Level (Unloaded Max.) | Unloaded | +/-25V | +/-6V | +/-6V | +/-6V |
| Driver Load Impedance (Ohms) | 3k to 7k | ≧450 | 100 | 54 | |
| Max. Driver Current in High Z State | Power On | N/A | N/A | N/A | +/-100uA |
| Max. Driver Current in High Z State | Power Off | +/-6mA @ +/-2V | +/-100uA | +/-100uA | +/-100uA |
| Slew Rate (Max.) | 30V/uS | Adjustable | N/A | N/A | |
| Receiver Input Voltage Range | +/-15V | +/-12V | -10V to +10V | -7V to +12V | |
| Receiver Input Sensitivity | +/-3V | +/-200mV | +/-200mV | +/-200mV | |
| Receiver Input Resistance (Ohms), (1 Standard Load for RS485) | 3k to 7k | 4k min. | 4k min. | ≧12k | |