PCIe-ICM-4SM User Manual
6
Functional Description
These cards feature high performance 16C950 class UARTs which support the complete
register set of the standard 16C550-type devices. The UARTs support operations in 16C450,
16C550 and 16C950 modes. Each port is capable of data communication speeds up to
3Mbps (standard model up to 460.8kbps in RS-232 mode) in asynchronous mode and has
128-byte deep transmit and receive FIFOs to protect against lost data in multitasking
operating systems, to help reduce CPU utilization and to improve data throughput. A crystal
oscillator is located on the card which permits precise selection of baud rates.
Serial protocol (RS-232/422/485) is software configured per port via a Port Configuration
Utility provided on the CD which ships with each card. When RS-422 or RS-485 are selected,
jumper selectable termination is provided per port.
Four-port models (PCIe-ICM-4SM, PCIe-ICM-4S, PCIe-ICM232-4) ship with an additional
mounting bracket and cable. This plugs directly into the dual 10-pin IDC headers on board and
mounts to an adjacent bracket slot.
Isolation
Ground loops
– current flowing through the ground line when ground voltage levels differ
between connected devices
– are a common problem frequently encountered in many
industrial applications. This situation can result in an increasing common-mode voltage
produced by the difference in ground levels and also by induced voltage typically from parallel
cabling that is carrying current to electrical equipment. Once the common-mode voltage
exceeds the capability of the transceivers to reject it, they stop communicating. Isolating serial
ports eliminates the effects of this problem and protects the computer system in harsh
industrial environments. RS-232 communications are even more susceptible to this condition
due to this architecture being only single-ended. This card is rated for 2,000V isolation from
port-to-port and port to computer for such applications.
Содержание PCIe-ICM-2S
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