Emerson PACSystems RSTi-EP function modules are available to meet specific system needs:
Digital Pulse Width Modulation (PWM)
PWM modules use positive logic to control small motors and valve flaps. The switching frequencies are adjustable up to 40kHz and the push/pull output levels can be used for motor activation and change of rotation direction. Available in two current requirement options, 0.5 (EP-5422) or 2A (EP-5442).
High-Speed Counter
Choice of 1- or 2-channel 32-bit counter with maximum input frequency of 100kHz (Pulse & direction or A/B mode with 1-, 2-, or 4-times sampling). Input filter time is adjustable from 0.01 to 1ms. They also feature an alarm and diagnostic function with μs time stamp.
The 1-channel version (EP-5111) can read one square-wave signal and count up or down within a predetermined range of values. The counter can be controlled using software or externally through the latch, gate, and reset inputs. The 1-channel version also features a digital output (0.5A with reverse polarity protection); that can be activated immediately upon either dropping below, meeting, or exceeding the set comparison value parameters.
The 2-channel version (EP-5112) can read two square-wave signals and, depending on the operating mode, both can count up or down independent of each other in a preset range of values. The counters can be controlled via software by setting the appropriate control word.
Frequency Measurement
The EP-5212 can read frequency of one square-wave signal from one or two external sensors with a maximum input frequency of 100kHz. It features a digitally adjustable input filter to suppress interference (17 filter frequencies gradually adjustable between 3Hz and 187kHz). Frequencies to be counted are applied to channel CH0 and/or channel CH1, the measurement will be started via control word 1 and 2 respectively. Measuring cycles can be defined in µs; the longer the measuring cycle the more exact the measurement. The module electronics supply the connected sensors with power from the input voltage path.
SSI Encoder
Interface module that can read differential signals (RS422) from an SSI encoder. It can be connected as a master directly to the encoder, providing the clock. To synchronize two SSI encoders a second SSI module running in "listening" mode can be placed between the encoder and master. Data can be formatted as binary or reflected binary (Gray code) and has a transfer rate of 125kHz to 2MHz. Connected sensors can be powered either with 5 or 24VDC. Both supply outputs are protected against over-current, and must not be used simultaneously. The SSI encoder must be connected using shielded wire.
Serial Communications
Serial data can be exchanged between the PLC and a data terminal device using the EP-5261 communication module. The device (such as a barcode scanner or printer) can be connected through an interface type RS232, RS485, or RS422. The data transfer rate can be set between 300 and 115,200 bps. The process data length can be set to 8- or 16-bit. A terminating resistor can be configured for the RS485 and RS422 interface respectively. The communication status is indicated by two LEDs on the respective plug. The module electronics supply the connected data terminal device with power from the input current path, either with 5 or 24VDC (select-able and protected against over-current).
