IS220PRTDH1A - Resistance Temperature Device Input Module

Functional Description

Processor Board Operation

The I/O pack or module function-specific acquisition board is connected to the processor board. The soft-start circuit ramps up the voltage available on the processor board when input power is applied. The processor reset is turned off, and the local power supply is turned on in order. After completing self-test routines, the processor loads application code from flash memory that is specific to the I/O pack or module type. To verify that the application code, acquisition board, and terminal board are correctly matched, the application code reads the board ID information. When a good match is found, the processor attempts to establish Ethernet connections by requesting a network address.

The dynamic host configuration protocol (DHCP), which is the industry standard, and the terminal board's unique identifier are both used in the address request. After Ethernet startup, the CPU runs the application, programs the on-board logic, and allows the acquisition board to start working.

The whole circuitry required to enable the I/O pack to function from one or two Ethernet inputs is contained in the processor application code. Both network pathways are constantly active when two Ethernet inputs are used. The I/O pack or module operation will not be affected by a failure of either network, and the functioning network connection will reveal the failure. This configuration is more fault-tolerant than a traditional hot-backup system, where the second port is only used when the primary port fails. The processor's Ethernet ports automatically negotiate between half-duplex and full-duplex operation at speeds between 10 MB/s and 100 MB/s.

The Processor Board Includes the Following:

• A fast processor with RAM and flash memory
• Two connectors for entirely independent 10/100 Ethernet ports
• Hardware reset and watchdog timer circuit
• Internal temperature sensor
• LEDs that indicate the status
• Capacity to read IDs on other boards and electronic identification
• An input power connector with a current limiter and a soft start
• Local power supplies, including monitoring and sequencing

IS220PRTDH1A Diagnostics

• A power-up self-test that examines the hardware on the CPU board, Ethernet ports, RAM, and Flash memory.
• Continuous monitoring to ensure the internal power supply is operating properly.
• Verifying that the hardware set matches by comparing the electronic ID data from the CPU, acquisition, and terminal boards and checking that the application code loaded from flash memory is appropriate for the hardware set.
• Hardware limit checking for each RTD type is based on predetermined (non-configurable) high and low levels near the working range's edges. Once the limit is reached, the input is no longer examined, and a logic signal is set.
• A composite diagnostic alarm, L3DIAG PRTD, referring to the entire board is generated if the hardware limits for any one of the eight inputs are reached. Information about each diagnosis is available from the toolbox.
• Individual diagnostic signals may be latched, and the RESET DIA signal may be used to reset them.
• System limit testing for each RTD input is done using customizable high and low levels. These limits, which can be enabled/disabled and set as latching/non-latching, can trigger alarms. The out-of-limit signals are reset via RESET SYS.
• The toolbox provides detailed information about each diagnosis. The diagnostic signals can be individually latched and, if they become healthy, reset with the RESET DIA signal.

Compatibility

RTD Input Terminal Board Compatibility

The RTD input terminal boards TRTDH1D, H2D, and SRTD boards are all compatible with the PRTDH1A, but the DIN-rail mounted DRTD board is not compatible. The compatibility information is provided in the table below.

System Configurations

• Simplex: One I/O pack and one or two network connections are used.
• Dual: Two I/O packs with one or two network connections are used.
• TMR: Three I/O packs with one network connection each are used.

The TRD input circuit is galvanically isolated by the PRTD. This requires modifications to the TRTDH1D and TRTDH2D boards' terminal board transient protection. The H1D version of the board provides filtering that is compatible with the PRTD standard scan rate. When the rapid scan rate of PRTD is chosen, the H2D version of the terminal board offers less filtering to ensure proper performance. Although there won't be any physical damage, if PRTD is mounted on an earlier version of the TRTD board, an incompatibility will be detected.