Symbol MK2000 MicroKiosk, Product Reference Manual

Page: 43 / 194

2-13
Installation
Wired RS-485 Setup
The MK2000 can communicate with a host via a wired RS-485 serial connection. Typically
the MK2000 Symbol approved AC power supply is used with this communications
interface.
For MK2000 devices installed where pre-existing PCK 9100, PCK 9140 or MK1000 wiring
exists, the pre-existing wiring can be plugged directly into the MK2000.
RS-485 is a two-wire multidrop network: RS-485 signal and RS-485 inverted signal, see
Figure 2-9 on page 2-15 for an illustration of the two-wire multidrop differential signal.
When installing an RS-485 configuration, ensure each MK2000 is connected directly to the
RS-485 bus, see Figure 2-8.
Figure 2-8. Connector Block
The cable required for an RS-485 installation should meet or exceed the following
specifications:
• 1 twisted pair 26 AWG (7/34) tinned copper
• twisted pair foil wrapped - 100% coverage
• nominal impedance 120 ohms
• capacitance between twisted pair 10-25 pf per foot
• capacitance between conductors & shield 20-35 pf per foot
• DC resistance of each conductor 45 ohms per 1000 feet
• DC resistance of shield 10 ohms per 1000 feet.
Wire nuts or connector
block may be used