Delta Tau: Serial Communications Optical-Isolation/Adapter Board (ACC-26A OPT1)

PMAC’s Accessory 26A is a new version of the serial communication optical isolation board for all versions of PMAC. It replaces the old ACC-26, which was suitable only for the PMAC-PC and the PMAC-VME. In the new version, ACC-26A Option 1 can be used for optical isolation of the host computer’s RS-232 to PMAC's RS-422 connector J4 (this is suitable for the PMAC-PC, PMAC-VME, and PMAC-LITE equipped with Option 9L).

The board comes with a standard DIN-rail mounting system, or you can use the four corner holes to mount the board with standoffs.

Both DB-9 and DB-25 connectors are provided for host connection.

Features:

Selecting the correct option:

When ordered as ACC-26A Option 1, this board comes equipped for RS-232 to RS-422 conversion and optical isolation. In this configuration, IC U1 plus resistor packs RP1 and RP2, are installed; IC U2 is not installed. ACC-26A Option 1 should be ordered for optically isolated host serial communication to the PMAC-PC, PMAC-VME and PMAC-LITE with its Option 9L. A 26-pin flat cable is provided for connecting this accessory's J1 connector to the PMACs' RS-424 connector (J4 on PMAC-PC and PMACVME).

Setup Procedure:

The ACC-26 requires very little setup. Simply connect it to the host computer through the DB-9 or DB25 connector; whichever matches your host's serial port. Do not connect both of these connectors, or you will get contention.

Jumpers on the ACC-26 are set up as default at the factory for the typical way a PC uses the serial communications lines (as the commanding device). If this is not the way your host device works, you can exchange the RXD and TXD lines by changing the E1A and E1B jumpers from horizontal to vertical, and exchange the RTS and CTS lines by changing the E1C and E1D (E2A & E2B in schematic) jumpers from horizontal to vertical.

Jumper E3 should be installed for Opt. 4 only (SMCC and MCC). Jumper E4 provides the choice between using the PMAC, SMCC or MCC power supply verses a separate power +5V supply brought in through the 2-pin terminal block TB1. An external power supply input through TB1 should be used for applications in which this accessory board is physically placed a long distance away from PMAC, SMCC or MCC. Otherwise, jumper E4 pins 2 to 1 for the motion control board supply of power to this accessory board.

Operating ACC-26A:

The ACC-26A requires no software setup, and can handle any baud rate up to PMAC’s maximum. Once installed and operational, it is transparent to the user.

There are four dual-color LEDs on the ACC-26A to show when the key communications lines are being used. Each LED is red when the corresponding line is not in use, and green when it is in use. LED D1 is for the RXD/ line, D2 is for the TXD/ line, D3 is for CTS, and D4 is for RTS. (These are the only lines that PMAC requires for serial communications; the ACC-26A shorts together the DSR and DTR lines for those hosts that require a return pulse on one, for a pulse on the other). These lamps can be used to troubleshoot communications problems. Lamp D5 is a green LED that is on when the card is receiving power.